PART III. BIOLOGY—OF THE WHOLE IN SINGULARS. (continued 7)

3017. Towards the termination of pregnancy, when the fœtus is endowed with muscular motion, the fœtal water is also absorbed. Nutrition is therefore in the commencement an absorption carried on by the integument, and lastly by the intestine.

2. Respiration.

3018. The respiratory organ of the fœtus is the chorion, and in particular the placenta. Its tissue is like that of the branchiæ or spleen.

3019. The arterial blood transmitted through the umbilical vein is conducted through the foramen ovale into the left ventricle of the heart, and from thence directly to the principal organ of the fœtus, the brain and spinal cord. From hence it returns, venous in quality, to the right side of the heart, and from thence through the ductus arteriosus into the inferior or descending aorta, from which, pursuing its course through the umbilical arteries, it again reaches the placenta, in which it undergoes a renewed oxydation.

3020. If therefore the umbilical cord be compressed, the fœtus dies suddenly, as happens indeed accidentally in certain cases, which completely resemble those of death produced by suffocation. The chick when in the egg dies, if the egg-shell be coated over with varnish, or if the egg be submitted to the noxious influence of gases which are devoid of oxygen.

3021. The respiration effected through means of the placenta, admits also of being proved by the sudden change which occurs in the circulation after birth. No arterial blood being then any longer brought to the heart through the umbilical vein, the left heart is no longer stimulated, and the foramen ovale collapses and is closed. Thus, all the blood enters the right side of the heart, and finding no thoroughfare into the ductus arteriosus, it is driven forcibly into the lungs, which now expand, and thereby leave an empty space between the pulmonary vessels, into which the air rushes in.

3022. The first act of respiration is therefore the result of the lungs being injected with venous blood, and thus of necessity ensues. When, on the contrary, cases arise causing pulmonary suffocation, the blood then regurgitates to the umbilical vessels, in order to reach the original branchia or placenta.

3023. Another process of respiration is found to take place in the vessels of the allantois. Its fluid becomes oxydized and penetrates through the urinary cyst into what have been called primordial kidneys. This kind of respiration through the anus is persistent in many Worms and larvæ of Insects.

3024. Finally, there is a respiratory process on the body of the embryo itself through the branchial apertures on its neck; these in the Frogs and Salamanders still continue visible after their exclusion from the egg. This oxygen must be derived from the fœtal water.

3025. Without doubt also the vitelline vessels respire, and thus each vegetative system has its own process of respiration. The intestine respires through the vitelline vessels, the vascular system through the vessels of the chorion, the sexual system through those of the allantois, the integument through the branchial apertures. The lungs belong to, and perform respiration for the whole body.

Decay of the Developmental Organs.

3026. When all the organs are developed, the intestines are drawn together with the vitellus into the abdomen. The chick is still nourished several days after exclusion from the egg by the vitelline mass, which passes through the vitelline canal into the intestine. The vitelline membrane subsequently becomes flaccid, and finally disappears through maceration. In the Mammalia the umbilical vesicle separates at an earlier period from the intestine, and continues to lie in the umbilical cord.

3027. The secernent point of the vitelline membrane or of the umbilical vesicle is the cœcum.

3028. There are therefore two intestinal systems, which branch off in a bifurcated manner from the cœcum, namely, the sexual intestine and the small or truncal intestine.

3029. All embryos have originally umbilical herniæ, which do not originate through protrusion of the intestines out of the abdominal cavity, but through their entrance into the latter being retarded.

3030. The umbilical herniæ therefore indicate an earlier condition of the animal, which has originated through arrest of the development.

3031. At birth all the enveloping membranes die, and their point of liberation is called the navel or umbilicus.

3032. The animal has originated through the umbilicus, and through this has it respired.

3033. All animals which breathe by the anus, do so properly through the navel; animals of this kind are fundamentally umbilical animals.

Parallelism of the Fœtus with the Animal Classes.

3034. During its development the animal passes through all stages of the animal kingdom. The fœtus is a representation of all animal classes in time.

3035. At first it is a simple vesicle, stomach, or vitellus, as in the Infusoria.

3036. Then the vesicle is doubled through the albumen and shell, and obtains an intestine, as in the Corals.

3037. It obtains a vascular system in the vitelline vessels, or absorbents, like as in the Acalephæ.

3038. With the blood-system, liver, and ovarium, the embryo enters the class of bivalved Mollusca.

3039. With the muscular heart, the testicle, and the penis, into the class of Snails.

3040. With the venous and arteriose hearts, and the urinary apparatus, into the class of Cephalopods or Cuttle-fish.

3041. With the absorption of the integument, into the class of Worms.

3042. With the formation of branchial fissures, into the class Crustacea.

3043. With the germination or budding forth of limbs, into the class of Insects.

3044. With the appearance of the osseous system, into the class of Fishes.

3045. With the evolution of muscles, into the class of Reptiles.

3046. With the ingress of respiration through the lungs, into the class of Birds. The fœtus, when born, is actually like them, edentulous.

3047. After birth it is suckled or fed. The milk is the nutrition continued by means of albumen; for the mammæ are verily only the albuminous vessels of the Bird, which are placed free and external in the Mammiferous animal. After the time for sucking is past the young one obtains teeth; and thereby becomes for the first time independent of the mother, and passes over into the class Mammalia. Now, should the sketch here afforded of these parallels be not in all respects correct or justifiable, still sufficient proof remains, that a perfect parallelism is found to take place between the development of the fœtus and that of the animal kingdom.

3048. Animals are only the persistent fœtal stages or conditions of man.

3049. Malformations are only persistent fœtal conditions, or animal formations in individual animal bodies.

3050. Diseases are vital processes in animals. Pathology is the physiology of the animal kingdom. A human fœtus is a whole animal kingdom. (Vid. Oken's 'Die Zeugung,' 'Beyträge zur vergl. Anatomie,' and 'Ueber die Nabelbrüche.')

Periods of Life.

3051. If the young in the ovum or in the mother's body resembles the aquatic animals, and has passed through their organization; so after birth does it belong to the air-breathing animals and traverse their organization.

3052. One period is that of sucking; the edentulous condition of the Bird. This is called the suckling age, baby-hood or infancy.

3053. One is that of the eruption and persistence of the milk-teeth; the condition of the Rodentia, a repetition of the gelatinous animals. This is the age of childhood.

3054. One is the eruption of the permanent set of teeth until the attainment of puberty, or the development of the sexual functions; the condition of the Marsupialia; repetition of the Conchozoa or Shell-animals. This is boyhood.

3055. From the state of puberty until the development of the faculty of understanding; the condition of the Shrews and Bats, the repetition of Insects. The age of youth.

3056. The period of the understanding passes through the Ungulata, and is a repetition of Fishes, Reptiles, and Birds. This is the first stage of manhood.

3057. After the understanding the reason matures; this is the condition of the higher Mammalia up to Man; it is a repetition of the Mammalia. This is adult age or mature manhood.

3058. Then follows the decadence or dying off of the sexual functions; a retrogression through the animal classes. Gray old age.

3059. Finally, the reason and understanding die; childhood returns and terminates with the death of the vegetable in the animal.

3060. Death results through the sexual animal.

3061. Death is only a continuous growth through retrogression into the organic primary matter or Infusoria.

3062. Death is an organized decomposition.

3063. Decomposition is a forming of seeds, ova, and fœtuses.

3064. Dying is a multiplication of self.

III. ZOOLOGY.

3065. Zoology is Zoogeny divided and self-substantially represented. What in Zoogeny was the organ of a single indivisible animal here becomes the organ of a separated animal, or becomes a self-substantial animal.

3066. The self-substantial animals are only parts of the Great animal, which is the Animal Kingdom.

3067. The animal kingdom is only one animal, i. e. the representation of animality with all its organs, each of which is a whole for itself.

3068. A single animal originates, if a single organ frees itself from the general animal body, and yet exercises the essential animal functions.

3069. The animal kingdom is only a dismemberment of the highest animal, i. e. of Man.

3070. Animals become nobler in rank, the greater the number of organs which are collectively liberated or severed from the Grand animal, and which enter into combination. An animal, which e. g. lived only as intestine, would be, doubtless, inferior to one which with the intestine were to combine a skin; and that animal again must be regarded as higher than the latter, which should present, in addition to these organs, vessels, liver, branchiæ, tracheæ, and lastly bones, &c.

3071. Animals are gradually perfected, entirely like the single animal body, by adding organ unto organ. The animal kingdom is developed through the multiplication of the organs.

3072. Each animal ranks therefore above the other; two of them never stand upon an equal plane or level. Animals are distinguished by their position of stages or degrees from each other, by the number of their different organs, but not by the division of a single organ.

3073. The animal system cannot be arbitrarily disposed according to this or that organ, just as it may chance to meet the eye; but only in accordance with the rigid prescripts of the animal body's genesis.

3074. The animal body separates into two series of organs, which, corresponding with, pursue a proximal course in relation to, each other; into the Anatomical systems and the Sensorial organs, unto which the sexual parts appertain.

3075. The number of the sensorial organs is 5, and they thus stand according to their genetic development one above the other:

Tactile sense or Skin. Gustatory sense or Tongue. Olfactory sense or Nose. Auditory sense or Ear. Optical sense or Eye.

3076. In animals, which are characterized by the sense of feeling or touch, the other sensorial organs must be either still wanting, or if present but imperfectly conditioned, i. e. not constituted like those of man, who is the type, pattern, or paragon for every formation.

3077. Their sensations are limited to those of general touch or feeling, and of those derived through the medium of the other senses we meet with but feeble manifestations.

3078. Their body itself will only be a tegumentary body, with the organs subordinated to the integument, namely, the viscera. They are therefore devoid of a true tongue, of a nose, and of ears and eyes consummated after the fashion of these organs in man; they are devoid of an osseous, muscular, and myelonal (spinal chord) system, and therefore of the nose "in toto," as being the anterior extremity of the myelon.

3079. Such are what have been called the Invertebrate animals, which are consequently, in accordance with their physiological signification, Splanchnic or Tegumentary animals.

3080. The tongue exhibits for the first time in Fishes a resemblance to the human structure, while their nose, ears, and eyes have not yet attained the latter grade of perfection. To the nose are wanting the posterior nasal foramina, to the ears the external auditory meatus, to the eyes the palpebræ and power of motion.

3081. In the Reptiles the nose opens for the first time into the mouth, and serves for the thorough passage of air. It is thus developed as in Man, while to the ears the external auditory meatus and cochlea are wanting, the eyes being barely endowed with lids and motion.

3082. In Birds, for the first time, the external auditory meatus, as well as the cochlea, is exhibited in its perfection, while the eyes are scarcely gifted with motion, and have only the inferior lid perfect; the tongue and nose, with the limbs also, have again become retrograde in character.

3083. For the first time, in the Mammalia, the eyes are moveable and covered with two perfect lids, without the other organs of sense having suffered degradation through this completion of the eyes.

3084. Thus in respect to the Senses there are only 5 animal divisions of equal value or worth. They should properly be called classes; but, as the lowest division, from comprising within itself the viscera or the vegetative systems, is very rich in contents; were we to call these divisions classes, many inequalities in rank, and hence also in the number of the orders and families, would originate—

1. DermatozoaInvertebrata.

2. GlossozoaPisces.

3. RhinozoaReptilia.

4. OtozoaAves.

5. OphthalmozoaMammalia.

3085. Now, with the sense of feeling, or the integument, the sexual system is associated or conjoined, and that indeed as the first or lowest development of the tegumentary system. Nevertheless, the sexual system divides into two groups, into the sexual organs, which are impressed with a true sensorial signification, and into their product, or the sexual juices, and the ovum or fœtus. With these two divisions the development of the integument proceeds "pari passu."

In the ovum the tegument and its contents are not as yet separated. Both consist of a transparent mucous or gelatinous mass, as is exemplified by the vitellus and albumen; such is the case also in the Infusoria, Polyps, and Acalephæ or Sea-nettles.

In the sexual organs, however, both parts separate into membranous capsules or cysts, and glandular contents, as in the roe or ovary; milt or testes; kidneys, with furthermore the oviduct, penis, and urinary cyst. The latter are sentient membranes. Such is the case in the Bivalve Mollusca, and Snails.

In the next place the tegument becomes, for the first time, a self-substantial organ of sensation by appearing as an envelope of the body; the vesical form is then repeated, and by this means the annular character originates as a series of cysts arranged one behind the other; it is thus a veritable skin, from which, finally, the members sprout forth, as in Worms and Insects.

The Dermatozoa will accordingly range in three stages.

1. Blasto- or Oozoa. 2. Sexual animals. 3. Cutaneous "

An annulated tegument, cutis or true skin, appears for the first time in the Worms, with here and there lateral filaments and tentacula. True feet and antennæ appear in the Crustacea or Crabs. Lastly, feet and wings in the Insecta or Flies.

3086. The external sexual parts, especially the male, first make their appearance, and that indeed with a very striking amount of development, in the Snails, and in like manner the body of the Bivalve Mollusca or Mussels has become almost a complete mass of ova or roe. In the Cuttle-fishes the first traces or rudiments of urinary organs appear. The animals which belong to this group are accordingly the Conchozoa or Shell-animals.

3087. Animals, which are directly resolvable into sexual fluids, or that represent parts of the ovum, are the gelatinous Infusoria, Polyps, and Acalephæ. Unto this category belong the Protozoa or Mucus-animals.

3088. The complete subdivision of animals, according to the organs of sense, would consequently stand thus:

I. DermatozoaInvertebrata.

1. OozoaProtozoa.

2. Glandular animalsConchozoa.

3. Cutaneous "Ancyliozoa.

II. GlossozoaPisces.

III. RhinozoaReptilia.

IV. OtozoaAves.

V. OphthalmozoaThricozoa.

3089. Unto these organs of sense the anatomical, or internal parts, are subordinated, and range parallel to them in a striking manner. The following is their order of succession in accordance with that of their origin:

1. Intestinal system. 2. Vascular " 3. Respiratory " 4. Osseous " 5. Muscular " 6. Nervous "

3090. That the vegetative systems are correctly arranged after this manner, is proved chiefly by their order of development in the animal series.

3091. The animals, occupying the lowest grade, are nothing but an intestine, which is in many instances scarcely separated or distinct from the tegument; they are devoid of vessels and branchiæ, and are barely provided with self-substantial ovisacs. Their body consists of one or two concentric cysts of an homogeneous and transparent substance—Intestinal animals, Protozoa.

3092. When the intestine is freed from the mass of the body, both then obtain the form and substance of tegumental cysts, whereof the external being only an intestinal tunic, thus represents the peritoneum. They are now, however, united by means of a vascular system, which is again surrounded by a cyst, and thus by a pleura. Their body consists of three concentric cysts; intestine, peritoneum, and pleura. It contains too a liver and self-substantial sexual parts—Vascular animals, Conchozoa.

If these cysts be repeated in the direction of the axis, the tegument becomes an annulated skin. An annulose animal is a multiplied cystic animal. Associated with this character, the respiratory organs are gradually evolved to form vascular plexuses, branchiæ, feet, tracheæ, and wings, while the sexual parts are for the most part separated—Ancyliozoa, Respiratory animals.

3093. The osseous system first appears in the Fishes, along with imperfect, mostly tendonless, and only white muscles, as also a myelon that is only developed into a stunted encephalon, in which the brain-organs of the Thricozoon are in great part wanting.

3094. Typical, or true muscles, provided with tendons, and of a red colour, are first exhibited in the Reptilia.

3095. A complete nervous system, pretty similar to that of the Thricozoa or Pilose animals, having a cerebrum and cerebellum, with similarly distributed and delicate nerves, is first displayed in Birds.

3096. According to the anatomical systems there are, therefore, six divisions of animals:

A.Splanchnozoa.

1. Intestinal animalsProtozoa.

2. Vascular "Conchozoa.

3. Respiratory "Ancyliozoa.

B. Sarcozoa.

4. Osseous animalsPisces.

5. Muscular "Reptilia.

6. Nervose "Aves.

3097. The Pilose animals first originate through completion and combination of all the organs of sense. They are Æsthetic or Sensorial animals.

3098. The arrangement of animals, according to the organs of sense, coincides consequently with that derived from the anatomical systems, and each animal division is therefore determined by two principal organs, by a vegetative and an animal. Every animal is at once a vegetable and animal body, the inferior kinds being partly so, but the highest or the Pilose animals entirely so, or in every respect, i. e. in them are found all the anatomical systems, and all the sexual and sensorial organs.

3099. The signification of animals is accordingly as follows:

I. Anatomical Systems.II. Organs of Sense.

A. Vegetative Systems.A. Tegumental Sense.

1. Intestinal animals.1. OozoaProtozoa.

2. Vascular "2. Glandular animalsConchozoa.

3. Respiratory "3. Cutaneous "Ancyliozoa.

B. Animal Systems.B. Cephalic Senses.

4. Osseous animals.4. GlossozoaPisces.

5. Muscular "5. RhinozoaReptilia.

6. Nervose "6. OtozoaAves.

7. Sensorial "7. OphthalmozoaThricozoa.

The ovum divides into vitellus, and albumen, along with the calcareous shell, and into germ or envelopes; the intestine into pharynx or stomach, bowels and absorbent vessels, thus:

1. Gastric animalsVitelline animalsInfusoria.

2. Intestinal "Albuminous "Polyps.

3. Absorbent "Involucral "Acalephæ.

The sexual parts divide into female, male, and urinary organs; the vessels into veins, arteries, and hearts, thus:

1. Ovarial animalsVenous animalsMussels.

2. Orchitic "Arterial "Snails.

3. Renal "Cardiac "Kracken.

The annulated tegument divides into papillæ, feet, and wings; the respiratory organs into tegumental network or rete, into branchiæ and tracheæ, thus:

1. Papillary animalsReticular animalsWorms.

2. Pedal "Branchial Crabs.

3. Alary "Tracheal Flies.

When parallelized with the organs of plants, the following remarkable relationships between them are rendered apparent:

1.CellsStomachVitellusInfusoria.

2.BarkIntestineAlbumenPolyps.

3.RootAbsorbentsEnvelopesAcalephæ.

4.DuctsVeinsOvaryMussels.

5.LiberArteriesTestesSnails.

6.StalkHeartsKidneysKracken.

7.TracheæRetiaPapillæWorms.

8.WoodBranchiæFeetCrabs.

9.FoliageLungsWingsFlies.

10.SeedsBonesTongueFishes.

11.PistilMusclesNoseReptiles.

12.CorollaNervesEarsBirds.

13.FruitSensesEyesThricozoa.

A. DIVISION INTO PROVINCES.

3100. The animal body divides first of all into the vegetative and animal. There will therefore be animals in which the former, and others in which the latter, systems predominate. The kingdom consequently separates into a vegetative and into an animal province. The vegetative parts are all tegumental developments, and thus the creatures in whom they prevail are Splanchnic or Visceral animals, but the animal parts are developments of the flesh, and constitute the Sarcose animals.

First Province. Splanchnozoa.

3101. Unto the Splanchnic or Tegumental animals are wanting bones, muscles with the nerves belonging to them, and thus the neural axis or encephalon; they are consequently devoid of bone, muscle, and brain, being in a word asarcose or fleshless animals.

The tegument is, however, the general organ of sensation or feeling; they are thus Sensitive animals.

3102. In them, developments only of the sense of feeling can occur, such as sensitive papillæ, tentacula, feet, and wings. All the remaining organs of sense can only be exhibited as rudiments of a very feeble or stunted character. They do not possess a true tongue, nose, ears, and eyes, i. e. constructed after the type of these organs in Man. The eyes only, from their being the sense of the animal system proper, can assume a definite kind of development.

3103. But, these organs of sense are the sensorial organs of the head, or rather are the head itself; the Tegumental animals are therefore devoid of a true head. They only possess such an one, in so far as it is determined by the tegument and nervous sense, by the mouth and the eyes.

These animals are what have been called Invertebrata, a name which is, however, defective, from its indicating the absence of one part only or of a single animal system, while the word flesh comprehends bones, muscles, and nervous mass; they are asarcose animals. But even this last appellation is not correct, because it is negative. Their positive system, or that under which they actually exist, is the tegument; so that the name of Dermatozoa or Sensitive animals, is the only proper one.

As the tegument includes the viscera and forms therefore the trunk alone, they may thus also be designated Trunk-animals.

Second Province. Sarcozoa.

3104. As in the animal body, bones, muscles, and encephalic system are suddenly associated with the tegumental system; so also does a second series of animals, having these systems, suddenly originate. Now, as the first formation of the osseous system is the vertebra, so all these animals have, as is generally understood, a vertebral column, and are on that account indeed Vertebrata; but, they are much more than this, and hence the title is of too limited a character. Besides there are among them animals, in which only the chorda dorsalis is present, without the ring of the vertebral body being formed around it.

Along with the animal systems the head is for the first time developed with its organs of sense—Cephalic animals.

These animals have consequently, in addition to the general sense of feeling, a true tongue, nose, ears, and eyes—Cephalæsthetic animals.

B. ANIMAL CIRCLES.

3105. Animal Circles are representations of entire anatomical systems as self-substantial bodies.

3106. Now, the vegetative body divides into three principal systems, into the Intestinal, Vascular, and Respiratory system, with their functions, or the digestive, nutritive, and respiratory processes. There are therefore Intestinal, Vascular, and Respiratory animals.

Circle I. Intestinal Animals.

3107. The intestinal system is the first form of body, or that from which the other systems have not yet separated. The body of these animals consists therefore of the homogeneous primary mass—the animal protoplasma, mucus or slime—Mucus-animals.

Now, the protoplasma is a hollow globule. The intestinal system is therefore nothing else than the original cystic form. Thus, there are Cystic animals like the Infusoria.

Again, cysts can increase in no other way, than by dividing into their like, or engendering cysts within themselves. The first kind of increase or multiplication of species is thus fissiparous, or produced by division.

The newly-engendered cysts are to be compared with the vitellus, and when they have attained perfection, to the ovum. They are therefore Oozoa or Ovum-animals.

In these animals consequently there are no separated sexual parts, namely, in addition to the vitelli, neither testes nor renal organs, or at least only obscure indications of them. In these Cystic animals the lowest feeling only, that of the sex or general sensation, can occur.

The Oozoa or Cystic animals, when compared with the plants, are the first flower that has been set free, or in other words, a flower which no longer stands polarwise upon a stem, because it is not developed in the differencing air, but in the indifferent water. It may be said that nature, having brought matters as far as the development of the sexual parts, then quits or passes out of the vegetable world; while these parts, or even the entire plant, requiring now no longer the stem and root, become a root themselves, and in behalf of this enter the water.

Animals, which have the form of flowers, are round or radiiform. There are Radiata or Radiated animals.

3108. These Anthoidal or Flower-like animals are Infusoria, Polyps, Acalephæ; being single or double concentric cysts.

3109. We may regard the Flower-animals as the fundamental mass of the sexual parts, which has attained unto free motion. They are sex throughout, or nothing but sex; it cannot therefore be said that they possess sexual parts like the plants, but that they are sexual parts. They are sexual parts that swim.

3110. Formerly, most of these Anthoidal animals were actually taken for real plants, on account of their floral and ramular form, and even their very substance; so slightly withdrawn are they from the vegetable kingdom. The whole difference between the two is effected by the water. Could we transpose them into the air, they would then become real plants.

3111. Now, as the vegetable flower is not a mere sexual system, but is also stock or trunk; so also is the animal flower at once an organ of digestion, respiration, and nutrition. The lowest condition of these organs is, however, only one of absorption, evaporation, and rigidification; these processes will therefore be present also, though only upon the lower stage—they are Intestinal animals; for in a simple intestine the same processes could occur, only within each other, whereas they are mutually dissevered or set apart in intestine, lung, and capillary system or parenchyma.

3112. The sexual parts are themselves viscera, or the viscera themselves are sexual parts, just as the fungus is at one and the same time root and seed-capsule. The sexual parts themselves absorb, respire, and nourish.

The floral sac is not therefore a mere sexual sac, but also an absorbent sac; upon a somewhat higher grade it is even a digestive sac, the sac-wall itself being a respiratory and nutritive paries or wall.

The sexual function has at once become an ingestive function, tending unto nutrition, or the deglutition of the food is itself an act of copulation.

The sexual capsule in these animal flowers can as well be termed stomach as uterus, and its wall ovary as well as branchia.

3113. As being of a sentient, mucous nature, they are point-substance or nervous mass. The tentacula are higher organized stamina, and thus occur as cilia, surrounding the oral aperture or mouth, as in the Infusoria. These palpi or feelers are, from being organs of ingestion, both male penes as well as digits or tongues, as in the Polyps. Their structure is still wholly tubular, while their elongation appears to be for the most part effected by injection with water—they are absorbents, as in the Acalephæ. The Oozoon brings forth young in the same cavity, in which it digests and by which it respires, and impregnates itself with the same filaments, whereby it seizes, swallows, and tastes its food.

In the bottom of the cavity of the Germ-animals, granules develop, which are born or escape through the floral opening—pharynx, and again become similar beings. In others the granules also sprout forth attached to the walls of the cavity, remain there some time united with the parent animal, and thus completely represent the mode of propagation in plants by means of gemmules or buds. Among the Polyps and Acalephæ it is well known that the ova issue from apertures near the mouth; while in the Actiniæ this is stated to take place from the stomach. The ovaria are, as is well known, situated between the stomach and parietes of the body.

3114. The intestinal animals are an entire animal organism, but only in the chaotic condition. They are the fundamental tissue, the cellular system of the animal, and the higher animals are only separated cells.

3115. The propagation is in every respect similar to that of plants. Now, as the seeds are the whole plant upon a small scale, so is the granule or ovum the entire animal; it is liberated through the pharynx and continues to grow merely by increasing in size. But if the young animal protrude through the tegument, that is a true gemmiparous propagation.

3116. Those Oozoa, which like plants can develop buds, consist of several animals, and may be cut in pieces like plants; when each piece becomes again an entire animal.

3117. The Oozoa represent those products of nature which are prior or antecedent to the animal world; namely, first of all plants, and further still the inorganic kingdom also, or the earth, since they have originated in the water and can be as well developed from the stones as the Lichens. There are therefore Lithozoa or Stone-animals, and Phytozoa or Plant-animals, among the Oozoa.

3118. Would we compare these animals with the parts in plants, they then represent their cell-development, or cells, bark and root. They are themselves either vesicles, as the Infusoria, or barks, as the Corallines, or a root-like fascicle of tubes, as the Acalephæ.

3119. In the animals, however, the cells have become stomach, the bark intestine, the root absorbents. The Oozoa represent therefore the aggregate of the intestinal system, the primary mass of the animal body.

Their whole body is a digestive body, or parenchyma, traversed in many species in all directions by tubes or absorbents, as in the Acalephæ.

As yet no nervous filament, nor any muscular fibre, &c. has been separated from their mass, as in like manner a tegument has barely been freed or separated from the intestine. These animals are nerveless and sine-tegumental, precisely because they are wholly made up of nervous mass and tegument.

Circle II. Vascular Animals.

3120. In the next place the digestive separates completely from the tegumental function, and each constitutes a function for itself, but which now being separated from its fellow could no longer subsist. Between the two therefore is formed the nutritive function in the vascular system.

Now, the vascular system of the self-substantial intestine is the liver. This organ will therefore for the first time make its appearance in this animal circle—Hepatic animals. Upon a higher stage, salivary glands are also developed on the intestine, and will here likewise begin for the first time to appear—Salivary animals, Snails.

3121. Through the separation of the viscera from the remaining substance, this must necessarily remain behind as a hollow cyst or tegument investing the former. The true free tegumental formation is therefore by no means accidental, but is necessarily bestowed with the viscera in the course of animal development. This tegument is peritoneum. There are animals which are invariably bicystic, but consisting of concentric cysts—abdomens.

Around the ventral integument, however, the vascular system also forms its tunic; this is the branchial membrane or operculum—pleura, mantle. There are tri-cystic animals—intestine, abdomen, and thorax disposed concentrically around each other—Mussels. Their body is therefore not articulated, but its parts are still inserted within each other.

The Vascular animals are consequently multiplied Protozoa; or Mucus-animals of the second power—Ovum².

The sense of feeling ascends upon its second stage, when its organ, having been freed from the mass of the body, surrounds the viscera as a self-substantial tegument. The feeling is then no longer one of a merely general character, but is a definite perception of external objects, a passive power of feeling.

3122. True muscles could not as yet originate in this skin, and that for obvious reasons, although fibres are present; for the former are to be brought under the signification of arterial fibres.

3123. Cilia, when furnished with fibres by whose agency they are rendered moveable and susceptible of inversion, are called tentacula, which here occur under every variety of form.

3124. Would we compare the Vascular animals with the plants, they must then represent their ducts, liber, and stalk. The heart is the stalk, the arteries liber, the veins tubes or ducts. These animals have assumed also upon the whole the cauline or cylindrical form—Cauline animals.

3125. From their having obtained in addition to the intestine only the vascular system, they are still governed by the water, and live therefore for the greatest part in this element. They have the first mode of respiration and thus an aqueo-respiratory process—possess branchiæ but not tracheal tubes.

3126. The sexual parts, which in the Germ-animals were still coalesced for the most part with the body, here become self-substantial through the separation of the teguments, make their appearance as a repetition of the digestive system under the condition of a free or separate system, and are evolved into true ovaria and even male parts—Sexual, Glandular animals.

3127. The first step towards the evolution of male parts is, however, only half achieved. Only one testis originates, while the other remains behind as ovarium—Androgynous or Bisexual animals.

3128. These animals, which are characterized by the vascular system, and by the first self-substantial or external sexual parts, which indicate organs of sense, are the Conchozoa, such as the Mussels, Snails, and Kracken.

Circle III. Respiratory Animals.

3129. When once the intestinal and vascular system, through perfection of their individual parts, such as the liver and branchia, and through separation of the sexual parts, are completed; then the individualization of the tegument steps into view, and it becomes an independent respiratory system.

3130. Through the increased process of oxydation the tegument hardens and is converted into horn. All induration, however, only takes place in opposition to soft places. The tegument therefore separates into hard and soft rings—Annulate animals.

3131. The annulate tegument is a tracheal tube wholly converted into a body. To distinguish it from the general tegument it may be called the cutis or skin—Cutaneous animals. The annular tegument may be regarded as a series of cysts placed one behind the other. The Annulate animals are therefore multiplied Malacozoa; Mucus-animals of the third power—Ovum³.

The respiratory organs, being in their lowest condition, will not as yet be freed from the tegument; the vessels simply form a network or projecting filaments and lamellæ—reticular branchiæ; as in the Worms. The tentacular organs, from being yet soft and thus scarcely moveable, are still very imperfect. Upon the lowest stage the tegument or skin simply feels; in the next place papillæ, and finally filaments, originate, especially about the mouth—Cutaneous, Papillary and Filamentary animals.

3132. If the tegument, as being the original branchial membrane, is converted into horn; then the branchiæ cannot continue as retia, but must elongate above the tegument into filaments, ramules or lamellæ.

With this, these elongated branchiæ separate into two organs, one part of them becoming indurated in like manner with the general tegument, and supporting the other as gill. Horny branchial filaments, which contain vessels, nerves, and fibres, are called feet—Pedal animals.

3133. The limbs or members of these animals are simply hollow tegument, hollow hair, and are therefore thoroughly different from the bones or the animal system.

The tegument thus hardens around the soft parts and the viscera. A horny coat of mail originates, and thus we have horny or mailed animals, in opposition to the Malaco-or Conchozoa.

3134. Beneath the horn, however, there must still be soft skin, and this becomes fibrous by the strong oxydation which it undergoes. Fibrous fascicles are attached to the coat of mail and to the hollow limbs, and are consequently within the tubes.

3135. These fibrous bundles are not flesh, but a fibre-drawn tegument, so that there are also no true muscles. They must on that account too be numberless.

3136. The articulations or joints are external not internal; they thus consist of tegumental tubes, not of bones, abutting against each other, and are not surrounded by flesh. Hence, like all the preceding groups they also are devoid of flesh—asarcose animals like all the preceding ones.

3137. In the branchiæ, however, it is only the cauline portions which become horny, while their ramules continue to perform the respiratory function. The branchiæ therefore are appended to the extremity or roots of the feet; or rather these latter form the branchial arches.

Annulate animals, having true or hornified and likewise annulated feet, are called Crustacea or Crabs.

Thus, in these animals the sense of feeling obtains special and moveable organs; they are Tactile animals.

Tactile organs are prolongations of tegument moved by muscular fibres, which in some degree adapt themselves by pressure unto the forms of objects, or have the power of seizing and retaining them—such as feet, antennæ, maxillæ, palpi.

3138. But if the tegument be entirely converted into horn, and the respiratory vessels have in this way disappeared within it, then the internal respiratory organs are formed by inversion of that part of the tegument which is between the rings, and through these openings the air penetrates to the internal parts—stigmata, tracheæ.

3139. The tracheæ can first of all originate when the respiratory process has attained its highest development, or, in other words, when the creature breathes air.

3140. Lastly, in the air-breathing Ancyliozoa even the external branchial lamellæ harden and are converted into wings—Pterozoa, Insects or Flies.

The wings of Insects do not correspond to the wings of birds; they are not feet, but pedal appendages or branchiæ, and thus are no new or unknown organ.

Circle IV. Sarcose Animals.

3141. The second animal province may be regarded as the fourth stage in the self-substantial development of the anatomical systems, although, properly speaking, it ranks as regards its value or worth upon a level with the three former circles, and resolves itself directly into three stages, which accord with its three systems. But since these stages are at the same time also classes; they should, for uniformity's sake, retain the latter name.

3142. The animal kingdom accordingly divides into four great districts or circles.

Circle I.Intestinal Animals,Oozoa—Protozoa.

II.Vascular "Sexual animals—Conchozoa.

III.Respiratory "Cutaneous " —Ancyliozoa.

IV.Sarcose "; Cephalic " —Vertebrata.

C. ANIMAL CLASSES.

3143. The animal Classes may be designated as the self-substantial representation of a stage in the development of an anatomical system or of the inferior organ of sense, and in the Sarcose animals of these systems themselves or of the cephalic senses.

3144. There are then as many classes as there are stages of development or systems. Thus the intestinal system separates into pharynx or stomach, intestine and absorbents.

3145. The vascular system into veins, arteries, and hearts.

3146. The respiratory system into branchial membrane or skin, into branchiæ, and into lungs or tracheæ, i. e. air-tubes. Taken in a strict sense, such divisions do not constitute classes, as has been already remarked.

3147. It is only the animal systems, which do not divide into several functions, but remaining upon a level with each other, are simply repeated in the higher organs of sense.

First Province. Splanchnozoa, Dermatozoa.

FIRST CIRCLE. INTESTINAL ANIMALS, OOZOA.

3148. The intestinal animals are nothing but depressed cysts. They rank therefore upon the lowest stage of development, and consist of mucus or granular nervous mass—Protozoa, Gelatinose animals.

3149. It is an established fact that, with animals as well as plants, the first function consists in imbibition or absorption, and the body must consequently be an absorbent cyst or a pharynx, which nevertheless takes up the food in the same way that the tegumental lymphatic vessels absorb. We can therefore style these animals pharyngeal or gastric, although the name is not perfectly correct—Infusoria. Then the intestine associates with the pharynx or stomach, so that they are Intestinal animals—Polyps or Corals.

Lastly the intestine sends out absorbents, and then the animal consists of pharynx or stomach, intestine and absorbents; such may be termed an Absorbent animal—Acalephæ.

The Intestinal animals therefore divide according to the developmental stages into three Classes.

Class 1. Gastric, Vitelline Animals.

3150. The lowest animals commence with the water, which has scarcely become mucus; they are nothing but drops, vesicles, which swim about independently—Protozoa or Primitive animals.

3151. The Protozoa correspond to the vitellus or the male semen, which is nothing but vitellus in a state of solution. They are the animal semen of the planet, the animal dissolved. Animal generation cannot take a deeper commencement or origin. The stone, which is decomposed into carbon mixed with water, can become nothing less than a point. They are the animal germinal powder. The fungus is a tissue of vesicles, which dissolves directly into seeds—fungus-powder or dust. Thus, they are ovaria or testes which have dissolved into seed, fluid testes—Vitelline, Seminal animals.

3152. The vitellus or semen is point-or nerve-mass dissolved. The Vitelline animals are sentient or nerve-points, which have combined all other processes in this identical mass. The divided point-mass ranks, however, in the signification of vesicular or cellular tissue. These animals are nervose cells.

3153. Nerve-cells must originate in every water, because every water is in a state of tension with the earth and the air; thus, dissolves the former and absorbs the latter. The water itself is a digesting and respiring mucus.

3154. The nerve-cells have an internal cavity, from the surface becoming oxydized and consequently converting itself into a denser layer, or into tegument. This, however, can only take place at the expense of the internal mass, as being that alone which abuts against the external parietes and becomes rigid.

3155. As the animal life is not simply a single act of rigidification, but a repetition of the same, alternating with solution, so must the Protozoon again replace the mucus-granules which have been disposed of from its interior; it must eat.

3156. It is a matter of indifference for the philosophy, whether the reception of food is effected by one or several mouths. There are Acalephæ and even Intestinal worms (Entozoa), which absorb by several mouths, almost like plants.

3157. But in the animal the mouth or mouths is or are definite organic openings, not merely interspaces or pores as in the plants; for they rank in the signification of the blossoms, or of composite parts.

3158. It can be therefore said that every animal hath a mouth or mouths, and consequently a stomach or stomachs.

3159. Their motions consist in abbreviations or straitenings of the cyst. Indications can scarcely be present of the secretions of higher organs, such as the intestine, vessel, branchiæ, liver, and such like parts.

3160. On the contrary, developments of the tegument and nerves may occur, the former as cilia which serve also as organs of motion and as branchiæ, the latter as ocular points or rudimental eyes; for both are none other than nervose tegument. The mouth of these animals is still passive, and subordinated to the water. It is surrounded only by cilia, which by the vortices produced by their movements in the water, impel or draw the latter into the mouth and with it the food. Such animals are called Infusoria.

3161. As the Infusoria are the seed or vitellus itself, so also are they the very ovum, and require no special sexual parts for propagation. They absorb, and are so nourished, and if there is a sufficient quantity of the mass to admit again of its division into several points, they thus divide. A magnified Infusorial animalcule has become, as it were, an ovarium or a testis, which then produces seed by dissolving itself into the latter. They are a constant conflict of the organ and its product, of the Solid and Fluid, a vitelline and orchitic process.

Class 2. Intestinal, Albuminous Animals.

3162. With the separation of the cyst into an internal and external layer, or into intestine and tegument, the animal must necessarily ascend a stage higher, since it now contains two systems different from each other, and is consequently a double Infusorium.

3163. The form of the Intestinal animals passes gradually from that of the globe into the tube—Tubular animals.

3164. They are tubular nerves surrounded by a tegument.

The cilia also are perfected and lengthen into filaments, which no longer perform simply vortical movements, but now actually seize and convey the food self-substantially into the mouth. Such animals are called Polyps. Their multiplication takes place no longer by division or fissure, but by ova and shoots, or ramification.

The oviducts or egg-tubes lie between the intestine and tegument, and open upon the margin of the mouth between the tentacula. In many instances the ovisacs, or cysts, hang also freely from other parts of the body, as in the Sertulariæ.

The sprouts or offshoots detach themselves from the parent and become independent animals; but they frequently continue to stand as ramules upon the maternal animal, though they nourish themselves independently of the latter.

3165. If the process of oxydation be augmented, then, the tube's external wall indurates, becomes coriaceous, and, lastly, ceratoid or horn-like in texture. The nerve-tubes or the animal proper can now swim no longer, since one kind only of motion is left it, namely, to protrude itself out of, and then retract itself within, the tube. It consequently falls to the ground, and while the external mucus hardens, it clings to the former; such are the Sessile or fixed Polyps.

3166. Sessile Polyps having coriaceous or horny tubes are called Plant-animals, Zoophyta, Phytozoa.

3167. The adherent, dried and dead external tegument of the Polyp is called stem. Such a ramified stem completely resembles a plant.

3168. These woody or herbaceous stems are not rooted in the earth, but have the power of adhering firmly to every substance, to stone, glass, shells, and such like bodies. They do not therefore draw in nourishment through any root.

3169. The ramification is often wholly plant-like in character, resembling that of a shrub with separate ramules, which even assume too the form of leaves, and the animal tubes that of flowers.

But frequently the ramules grow together also by their extremities, giving rise to a trellis-work, the production of which in plants is impossible. The soft animalcules, which come in contact, cleave unto each other, and grow together like wounded parts in the Sarcose animals.

3170. Upon the surface of the ramules or the leaves are apertures, out of which the mucous substance protrudes the radiated mouth. But these mouths are frequently, especially in the Cystic corallines, of two different modes of formation. The one kind are cysts without filaments, and contain ova, which are developed and fall out. The others have filaments, which move and do not produce ova. The former look like seed-capsules, the latter like flowers with stamina, while the entire trunk resembles a monœcious plant.

3171. With increased oxydation calcareous earth is deposited in the external tegument or rind, and the stem is converted into stone—Lithozoa, Lithophyta, Corals.

This calcareous earth contains the most general acid, or the carbonic, and thus oxygen combined with the inorganic carbon, while the bones contain phosphoric acid, oxydized gelatine.

3172. As the calcareous earth is, properly speaking, only a granular deposit in the tegument, like it is in the cartilages of the higher animals; so is it not to be regarded as a free worm-tube, but as the body itself. Meanwhile it forms a tube open above, from which the mouth of the animal projects.

3173. As the animal ramifies, so also do the stony tubes increase, and there originates a phytoidal or plant-like stem, but one consisting of a stony mass.

3174. Thus the Coral is the earth-animal, and indicates the globular or osseous mass under its first grade of formation in the animal kingdom.

But there are also Polyps, whose stem only originates through saccular inversion of the upper portion of the animal's body; yet this is only distinct in the soft stems. In most of the species, where a separate intestine is to be found, it is probably only the upper part of the body which is so inverted. Meanwhile there are some, whose intestine forms a circle by returning upon itself, and opens into an anus.

3175. If then the Infusoria are the vitellus or seed of the animal kingdom; in like manner the Corals are its ova. The carbonate of lime is the shell surrounding the albumen, while the animal or intestine is the vitellus—Albumen-animals.

3176. Nature forms these living ova, when she takes vitellus and albumen out of the sea-slime, invests them with a shell derived from the earth, and hatches them, after they have been vivified by sun and air.

Class 3. Absorbent, Involucral Animals.

3177. Did the former animals remain in the condition of ova, from want of a perfect vascular system; they are next developed, so soon as vessels appear and form a vascular plexus, into fœtal involucra or envelopes. These animals are vitellus with the vascular membrane.

3178. The Absorbent animals are no longer simple vesicles, but large cysts or capsules like the developmental envelopes of the fœtus, along with a choroid plexus—Involucral, Fœtal-animals.

This choroid plexus does not, however, consist of arteries and veins; but is only a ramification of the intestine, so that the vessels are of a lacteal character—Absorbent animals.

3179. In these animals there is no longer any egg-shell, but everything has been taken up into the galvanic circle; the shell has itself become organic and life-imbued. Their substance is still mucous or albuminous; they are still vitellus, though converted into a vascular tissue.

3180. They therefore cling firmly nowhere; but swim about freely, like brain-masses converted into radiated cysts.

3181. Free Mucus-animals, traversed by vascular plexuses, are Acalephæ.

3182. There are Acalephæ which are simply air-sacs, like the air-sacs of ova, to which hang ramified vessels as absorbent tubes—Cystic, Tubular Acalephæ.

Others represent hemispheres with numerous absorbent tubes, which concur in the middle of the animal to form a kind of stomach, from which again other tubes pass towards the border, in order to elongate into tentacula. Thus the absorbent vessels have become motor and sensitive organs.

Besides this, many have around the mouth four large lobes, which must be viewed as the antetypes of the sentient lobes of the Bivalve Mollusca.

Lastly, others have a true mouth, which leads to a similar gastric cavity, out of which the same vessels emerge and ramify. Both kinds are called Hutquallen or Acalephæ.

There are yet others having the same structure, but oviform, with respiratory lamellæ upon the absorbent tubes, Rippenquallen or Beroes.

3183. An Acalephan is a brood-egg, which swims freely about without a shell.

3184. The vessels are quaternary in their distribution, and form a cross, like the involucral vessels of the chick.

3185. In these animals the ova first begin to be detached and agglomerated together in definite situations so as to constitute ovaria. The number here is also four.

They lie usually within four cavities surrounding the stomach, and into these wide apertures situated near to the mouth lead; they are at the same time regarded as respiratory cavities.

In other species vesicles, wherein seminal animalcules are developed, occupy the same situation. Here therefore is recognised for the first time a separated sex.

In the Röhrenquallen or Physaliæ the ovisacs mostly depend externally in the form of bells.

Besides this we find in the Acalephæ all sorts of laminæ, which are probably organs of respiration.

It is not known what is the meaning of the air-sacs and of what the air consists.

Most of the species emit light like globes of fire, just as many Infusoria do also. It is probably a phosphorescence given out by the mucus when passing over into a state of decomposition.

Very many have also the stinging property of the nettle; but, whether the cause of this is chemical or mechanical, is not yet exactly known.

SECOND CIRCLE. VASCULAR, SEXUAL ANIMALS.

3186. So far, or in the ascending scale up to the Acalephæ, the animal is only viscus with an absorbent canal, which is at the same time a canal of evacuation, without a distinct intestine being set apart for that purpose; such is the general rule.

3187. After the Acalephæ the formation undergoes a change; the distinction between the exterior and interior is prominently displayed, and the internal wall becomes freed as a separate and perfect intestine along with a mouth and anus; the external wall appears as a free tegument. But, seeing that two concentric and separated cysts could not subsist without combination by means of the nutritive system or the vessels; a perfect vascular system is formed, divided into veins, arteries, and hearts.

The tegument, wherein the vessels become self-substantial, is the branchial membrane. There is therefore placed around the intestinal body a vascular body also, or branchial membrane, which is consequently pleura or mantle (pallium), as in the Mussels. The body of the intestine consists of intestine and peritoneum; that of the vessels of branchiæ and pleura or mantle.

These animals are hence bisystemic, being both Intestinal and Vascular animals; but, since the vascular system is a new addition, it is thus characteristic of the circle, and its members must be therefore called Vascular animals. With the vascular system, however, all its further developments have been bestowed; thus especially the complication of the vessels with the intestinal ramifications or, in other words, the liver—Hepatic animals. The salivary glands also are a similar complication, and in this series therefore they make their appearance.

Lastly, the renal glands are such a kind of vascular organ, or branchiæ of the sexual parts; they also begin to be astir in this series.

With the separation of the systems into separate teguments or membranes, the sexual parts also separate. The ovarium becomes an independent organ furnished with its own excretory ducts; the male parts are individualized to form veritable testes furnished with excretory ducts, or even with a penis. Still this is all effected only by degrees, or as yet within the confines of this circle.

These animals divide according to the viscera into Venous, Arterial, and Cardiac animals; according to the sexual parts, into Ovarial, Orchitic, and Renal animals.

Class 4. Venous, Ovarial Animals.

3188. With the protrusion into view of the vascular system, the veins are chiefly developed along with their principal organ, the liver, as being the bond of union between the circulation and the intestine.

3189. The animals, which first bring to bear in addition to the intestine a liver, are the Bivalve Mollusca.

3190. With the veins arteries also originate, but with a preponderance of venosity or the venous character. The blood is lymphatic, colourless.

3191. The cardinal venous organ or the liver evokes also into existence a corresponding organ of respiration, namely, free branchiæ with the tegumental form—branchial laminæ or leaves.

3192. In the middle between the branchial laminæ and the liver, the heart is evolved; this organ comprising always a ventricle with an auricle, but consisting of a venous, membranous tissue almost devoid of fibres.

3193. The first heart is in other respects arteriose; it receives the blood from the branchiæ and transmits it to the liver as well as to the remaining parts of the body, from which it proceeds directly to the branchiæ without entering any venous or right heart.

3194. In these animals, as is well known, four branchial leaves lie externally on the belly, which includes the intestine with a large liver, and hangs together with the branchiæ as a separate purse within the mantle.

3195. In the Mussel a structure originates for the first time, which can be compared with a thoracic or pectoral cavity. What covers the branchiæ, must stand in the signification of the thorax or chest. The pallium or mantle of the Mussels is pleura.

3196. Their shells are branchial opercula (as in the Fishes). They are secretions from the mantle, and everywhere accompany the branchiæ.

3197. The locket or hinge of the shell-valves corresponds to the rachis or spina dorsi, as is especially distinct in the Teredines or "ship-worms."

The shells of Bivalve Mollusca are a calcareo-thoracic box, open in front, inverted behind, and moveable like ribs.

3198. The two sphincter or occlusor muscles signify shoulder and haunch.

3199. These animals begin for the first time to exhibit bilaterality or symmetry, because in them there is stirring the idea of the osseous formation. From the branchiæ being situated symmetrically upon both sides, the cardiac chambers are also symmetrical.

3200. The pectoral tunic (mantle) usually elongates at the anal extremity into two tubes, respiratory tubes, through which the water is drawn in and thrust out or expelled. Such is the case in the highest Worms or Holothuriæ, only there the respiratory tube leads into the body itself. A similar arrangement is found in the Echini. Many aquatic larvæ from all kinds of Insects or out of different classes breathe through anal tubes. All these animals consequently repeat the Mussels, and this formation admits of being followed out up to Man, where it is left as allantois and primordial kidneys. The thorax of the Mussel thus opens by the anus. But, since the thorax is that which is here preponderating and is nearly the whole animal, so does the anus open into the posterior respiratory tube.

3201. The Mussel can be regarded as an animal consisting of three cysts or sacs inclosed within each other, namely, of intestine, around this the ventral pouch, and around this again the thoracic sac or mantle. If, moreover, the shells be regarded as a cyst, the animal then consists of four sacs. The heart and branchiæ lie within the thoracic cavity; intestine, liver, and ovarium within the abdominal or ventral cavity. The Mussel is thus a doubled Acalephan.

What is termed foot in the Bivalve Mollusca is nothing else than the abdominal tegument dilated in front to form a muscular ridge.

3202. The Mussels are embryos, in whom the liver originates, and whose chorion acquires a placenta. Then again, as the embryo is nearly all liver, and hangs surrounded by a watery fluid within the widely-expanded chorion and amnion, so does the abdominal pouch hang within the pallial cavity, or in the wide, water-full chest.

3203. In the abdomen there is still only the ovarium, and that indeed very large. There are properly two ovaria, each of which, according to my observations (vid. Göttinger Gelehrte Anzeigen, 1806. Stück 148), opens laterally under the shoulder-muscle and gives exit to the ova, which then enter within or between the branchial fringes, in order to be there developed.

3204. Here the respiratory organs are still at the same time a kind of uterus. The ova may be oxydized therein, like the embryo is in the uterus. These branchiæ are probably still to be compared with, or designated as, sexual branchiæ.

3205. In the back of the shoulder these animals have a highly vascular organ with two excretory passages, which open near to the orifices of the oviducts. I formerly regarded it as a kidney, but, according to more recent observations, it should be a testis. In the anterior part of the foot there is frequently situated a gland which ejects a gelatinoid moisture, which hardens into glutinous filaments—the byssus or beard. It is probably a memento of the tentacula of the Acalephæ. There is besides also an organ in the feet of many Bivalve Mollusca, which occasionally squirts a watery juice out to a great distance. I have occasionally found this organ in our Teichmuschel. Its signification is probably the same as that of the preceding organ.

3206. The organization of the Bivalve Mollusc can be thus most distinctly described; it is an abdomen, wherein is an intestine with mouth and anus, a liver and a double ovarium; upon the sides of this abdomen are situated the branchiæ in the form of four laminæ; around the branchiæ and the abdomen is the pleura or mantle, which is always open posteriorly.

3207. The mouth is placed directly at the anterior extremity of the abdomen, is devoid of neck and head, as also salivary glands; it is consequently not a true mouth, but only a pharyngeal aperture. Thereupon, however, are situated four sensitive lobes, which are in structure exactly like the branchiæ—cephalic or pharyngeal branchiæ. They are the further formations of the four arms of the Acalephæ.

3208. The Mussel has a perfect splanchno-neural system with ganglia and a pharyngeal ring, which probably corresponds to the nerves that sweep around it.

3209. The Mussel has no other organ of sense than that of the passive sense of feeling, the tegument. It cannot once move its sensitive lobes voluntarily; it has no lips.

3210. The abdomen only elongates in most of them to form a moveable, variously constructed foot or keel, which cannot, however, creep but only push. The progression of the Bivalve Mollusca is backwards, as in the Acalephæ. In the Snails the ventral surface first becomes a creeping sole.

3211. The Mussels repeat the Infusoria; are Infusoria with a bivalve calcareous testa or shell.

Class 5. Arterial, Orchitic Animals.

3212. In the preceding class of Bivalve Mollusca, it is in truth the abdominal viscera only, such as the intestine, liver and ovarium, which have been perfected; and then the veins and arteries with a membranous heart. The cephalic organs, eyes, maxillæ, salivary glands, and even moveable lips with tentacula, are wanting, as well as the muscular heart. Lastly, the arterial sexual system or a self-substantial testis and the penis were absent.

Now, Mollusca, which have eyes, maxillæ, a muscular heart and a ventral sole or foot, with salivary glands and a penis, are Gasteropoda or Snails.

3213. The Snails possess salivary glands, a trace of the tongue and of maxillæ, moveable lips and tentacula, with thus an approximation to the head, unto which the eyes are rarely wanting—Salivary animals.

3214. With the development of the head or rather of its inferior organs of sense, the antagonism makes its appearance also in the ovarium. A half of the ovarium is converted into the testis.

The Snail is therefore a Mollusc, which is female upon one side, male upon the other.

3215. The androgynous or bisexual animal is, as a general rule, asymmetrical.

3216. The mantle also or the branchial cavity obeys this want of symmetry. The branchiæ of one side dwindle down; those of the other turn with the mantle towards the head, and the respiratory aperture occurs upon the back.

3217. With the one-sided evolution of the mantle, one shell also is only developed, while the other is stunted or placed under arrest. The Snail's shell is one of the Bivalve Mollusc's shells, its operculum is the other. This last is stony, horny, and finally is entirely wanting.

It is remarkable that the right shell has been pretty generally perfected, while the left dwindles down into the operculum; all the Snail's openings are therefore upon the right side, such as the anus, with the orifices for the escape of the ova and semen.

Male animals are situated on the right side, female on the left; or where the right side was predominating, there originated the male sex, where the left, the female.

3218. As the orifice of the mantle and the shell is properly the aperture of the branchial foramina; so can it be said, that the Snail were a Mussel, which does not simply extend the foot, but also the mouth or head to the branchial opening; it is a Mussel reversed.

3219. Every thing else in the Snails is arranged in accordance with these fundamental organs and forms.

The cephalic portion of the intestinal canal is indicated also by muscular fibres. The pharynx and the mouth can contract and expand, seize and bite off; the former frequently admits of being protruded and retracted as a fleshy proboscis with perforating maxillæ.

3220. Since the muscular fibres are only tegumental fibres, and therefore lie within cavities; they thus act like as in the feet of Insects.

The tentacula of many Snails are moved like the feet of Insects; but as they are not horny, but soft, they are turned either inside out or "vice versâ." The oviduct and seminal duct or penis follow the same mode of formation. They are likewise everted and inverted.

3221. These members of the Snail are true Insect-limbs that have remained soft, and are thereupon susceptible of inversion and eversion. Were an Insect's foot soft, every one will admit that it would then yield so as to become inverted, if the fibres pulled upon it. The limbs of Insects have thus only become stiff, and are thereby Snail's horns that resist inversion. All these members are teguments, and give the lie only unto limbs; for it belongs to the essence of a limb, that it be dense.

3222. That which suffers eversion or its converse is no limb, but only a sheath, a prepuce. Nearly the whole Snail is but a prepuce, a "membrum virile" or "verge."

3223. There is no class of animals, in which the testes and penis are found so disproportionately developed as in the Snails—Orchitic, Penes-animals.

3224. The vascular and nervous systems are related pretty nearly as in the Mussels. But the heart is fleshy and has, by reason of its unilateral or single branchia, only one auricle also.

3225. The Snails repeat the Corals in the cylindrical form of the body, the tubular-shaped shell, and the return of the intestine upon itself towards the mouth, as in many Corallines.

3226. In them also the organ, which virtually corresponds to the kidney, appears to be astir, namely, what has been called the calcareous gland, situated within the branchial cavity, and which opens not far from the anus.

Class 6. Cardiac, Nephritic Animals.

3227. Hitherto there has been found only a single "cardia," namely, the left or arterial heart, which, receiving the oxygenated blood from the branchiæ, propels it to all parts of the body—for the purposes of nutrition. But now also the right heart suddenly makes its appearance, which drives the blood into the branchiæ—for oxygenation. This must doubtless be regarded as a higher development, especially since, as I have shown, in the higher animals as well as in the embryo, the right heart is first perfected subsequently to the left.

The Conchozoa with a double heart are the Sepiæ or Cuttle-fishes. These are in consequence correctly called Cardiac animals, and must be regarded as the fundamental form of this stage.

With this completion of the heart other structural changes, which probably stand in intimate connexion with it, appear. In the Snails indeed a kind of renal organ, or what has been called the calcareous gland in the branchial cavity, has been already shown to exist. Whether the shoulder-gland in the other Mollusca belongs also to the members of the present class, may be left undetermined. This kidney, like other vegetative organs, pours out its secretion quite involuntarily. In the Cuttle-fishes it is, however, combined with an organ, by means of which it can discharge its fluid, or the ink, voluntarily as in the higher animals. The kidney or ink-gland with the ink-sac is therefore characteristic likewise of the Sepiæ, and admits of our calling these creatures Nephritic or Renal animals.

At the same time the whole form of the body is altered; it becomes cylindrical, and is provided upon the ventral aspect with neither a muscular keel nor sole, whereby it might glide or shove itself along; thus herein also a resemblance is manifested to the higher animals.

This motionless body is on the contrary endowed with independent organs of locomotion, namely, with fins or arms, which are wanting in the Snails and Bivalve Mollusca. The labour of motion is consequently removed by the organs which minister unto it from the body, and thus we trace another similitude to the higher animals, which transport their body from place to place by wings or feet. These animals can be therefore called Cylindrical Snails, out of contrast to the Sole and Carinate Snails or the Bivalve Mollusca.

Closely allied now to these cylindrimorphous Conchozoa are all those Mollusca in whom the keel (carina) or sole is wanting; i. e. such snail or mussel-like animals, which either cannot transport themselves at all, or effect this by means of fins or podoidal appendages, in short all that have been called Snails, having no sole, and all supposed to be Mussels, but without a keel.

Now, the Heteropoda or Pterotracheæ and the Pteropoda or Clionæ have projecting processes which act like fins.

The Brachiopoda or Terebratulæ, though unendowed with the power of locomotion, have, as their first name implies, arm-like organs.

The Cirripedia or Lepades, being likewise without the power of continuous motion, possess podoidal or foot-like appendages. In both these families, however, these appendages are nevertheless true motor organs; for by means of them they seize their food, an act which hitherto has been seen to take place neither in the Snails nor Bivalve Mollusca.

Lastly, the prehensile organs dwindle down into mere filaments or small lobes, but the body always retains its cylindrical form without keel and sole, as in the Ascidiæ or Meerscheiden.

In the Salpæ only the cylindrical body is left, unto which appendages are still, and not rarely either, attached, serving them wherewith to lay hold of each other. In accordance consequently with their external form all these animals appertain to one class along with the Cuttle-fishes. I call them Kracken.

The renal organs are still not to be found in all of them; the structure alone of the heart agrees essentially, despite of its simplicity, with that of the Cuttle-fishes. In the Ascidiæ, simple as well as compound species, it is indeed but a single, though muscular pouch. Now, this pouch drives the blood alternately, at one time into the branchiæ, at another backwards into the body, and is thus in the first act a venous or right heart, in the latter an arteriose or left; consequently, according to function this single pouch is compounded or made up of the two hearts.

The branchiæ deviate entirely from those of the Mussels and Snails, and exhibit a very complicated structure; in the mussel-like families they present the form of a trellis-shaped sac, as in the Ascidiæ, or that of filiform appendages to the feet, as in the Cirripedia, or they are funiform as in the Brachiopoda. In the Pteropoda they are very varied; in the snail-like Heteropoda they are mostly pectiniform or tuft-shaped; in the Sepiæ or Cephalopoda phylliform or fin-shaped.

The external character ccommon to the whole class is the cylindrical body, unto which may be aptly conjoined the possession of special organs of motion; whether such organs be prehensile in function, media of support, or veritable instruments of progression.

The snail-like Pteropoda, Heteropoda, and Cephalopoda, have a head, but this is wanting in the mussel-like Salpæ, Ascidiæ, Cirripedia, and Brachiopoda.

THIRD CIRCLE. RESPIRATORY, CUTANEOUS ANIMALS.

3228. Respiratory animals are Dermatozoa with a predominating system of respiration.

Now, the respiratory system is the tegument, which here then must attain the highest pitch of perfection.

This again takes place through the increased process of oxydation, which produces induration of the parts.

The vessels, which surround the tegument, must nourish this portion of it to a greater degree and render it harder or more compact than any other, whereby alternating expansions and contractions thereof originate, in other words, the structure of the trachea.

3229. The whole body of the Respiratory animals becomes a trachea, a series of rings. The Respiratory are therefore the Annulate animals.

The rings are to be regarded as cysts, which are mutually juxtaposited or repeated, not being inserted within each other as in the preceding animals, but behind each other, so that the present circle consists of multiplied Cystic animals.

3230. The Annulate animals must represent the developmental stages of the tegument, while the viscera make a retrograde step—Tactile animals.

3231. The tegument has two functions: it is an organ of respiration and of general feeling or sensation. In both cases it passes through three stages of development.

It is either entirely a branchia, i. e. reticular in character; or the branchiæ become individualized in certain situations and partly horny, constituting branchiæ proper; or finally, the tegument is converted into an air-breathing organ, tracheæ or air-tubes.

3232. It either feels with its whole surface, or by papillæ; or the branchiæ change into horny feet; or lastly, into alary appendages or wings. The Ancyliozoa consequently divide into Reticular or Papillary animals; into Branchial or Pedal, and into Tracheal or Winged animals.

3233. As the arterial character preponderates in these animals, so do the venous organs, especially the liver and renal structures, retrograde.

3234. The body is now an intestinal and tegumental body with predominating respiratory and sentient organs; here therefore sensitive papillæ, antennæ, feet and wings, appear in abundance.

3235. With the retrogression of the viscera, the glandular structure also and large proportional bulk of the sexual parts disappears. They assume the form of the intestine and tegument, i. e. become tubes.

The spawn like the milt consists, as a general rule, of only two long membranous tubes, running near the intestine.

3236. The external sexual parts belong to the sense of feeling and follow the developments of the tegument; they make their appearance as antennæ, and are usually accompanied by foot-like accessory organs.

3237. The nervous system in like manner accompanies the tegument. It consists of two gangliated cords passing along the ventral surface.

3238. As the maxillæ are only repeated feet, so they are rarely wanting, and are, like the latter, disposed after the fashion of scissor-blades. The same holds good of the antennæ; they are mostly in pairs, and consist of a series of rings projecting from the head.

3239. The eyes are usually present, but only as tegumental organs, or placed upon the points of the antennæ.

Class 7. Reticular or Papillary Animals.

3240. The repetition of the Intestinal or Vascular animal, taking place under the dominion of the respiratory system, must be accompanied by the vascular system. The tegument is a vascular, a branchial membrane, a branchial network or skin.

3241. A body with predominating tegumental and intestinal system, is cylindrical. It can only become gross or lump-shaped, if the glandular viscera, such as liver, ovarium and testes, get the upper hand or prevail.

3242. A tegument which appears as a branchial membrane, is annulate or ringed.

3243. An animal, having an annulate respiratory membrane without annulated feet, is a Worm.

Upon the lowest stage the vascular system is still similar to that of the Vascular animals; its blood is a colourless fluid—White Worms, Entozoa.

In order to be a Worm, it is sufficient to have an annulate tegument. Even if the intestine be wanting and the tegument supplies its place; the character is nevertheless complete. Here it is the skin, which digests, while in the Intestinal animals it is the intestine, which digests and breathes. Since it is here the tegument, which undertakes the offices of the whole body; the vessels, liver, and salivary glands are wanting unto the intestine.

The sexual parts are also frequently arrested and the ova appear to originate in the tegument.

Many undergo division without injury to themselves; yet the detached portions do not become again entire animals.

In most of them, however, the sexual parts of both sexes are present, being associated with, though separate and distinct from, each other; those of the female mostly opening upon the sides of the body.

As being Dermatozoa, they have for the most part special organs of sensation around the mouth, under the form of papillæ, filaments, spines and cups. The nervous system, wherever it is to be met with, consists of a ring surrounding the pharynx, and of a double ganglionic cord lying along the ventral surface of the body.

3244. Upon a higher stage of development the arterial system gains the preponderance, and the blood becomes mostly of a red colour—Red-blooded Worms.

3245. With the arterial the fibrous system also makes a more decisive appearance. The tegument is a fibrous tunic—it is itself an artery. All Annulate animals with a fibrous tunic, which can consequently contract, belong to this class, whether too they have red blood or not, like the Holothuriæ and Star-fishes.

3246. The Lumbricales or Earth-worms and the Hirudines or Leeches respire obviously through the whole tegument, though a special organ of respiration does begin to be evolved, in the first family in the "saddle," in the second in the lateral vesicles or cysts.

3247. In others the branchial vessels make their appearance above the level of the tegument as filaments or ramules, and are arranged in two rows, as in the common Sea-worm and in the Nereides.

3248. Lastly, they accumulate about the neck or head, as in the Amphitrites and Serpulariæ.

3249. There are also Worms which respire only through the intestine, its vascular system being bathed on all sides by water, as in the Aphroditæ. This water becomes, as it would appear, simply imbibed by the tegument in Thalassema, but through an opening at the anal extremity of the body in the Holothuriæ.

3250. These Worms have also no liver, or at the very best only traces of that organ, by reason of the preponderance of the arteries.

3251. Papillæ or sensitive filaments gradually sprout from the external branchial filaments, lie along the sides of the body, and are the prelude of the feet; as in the Nereides—Papillary, Filamentary animals.

3252. Others of these filaments become horny and appear as setæ or bristles, placed somewhat similarly to the above, as in the Earth-worm.

3253. Mouth and head are more perfectly developed than in the Entozoa. The first can readily expand and contract, frequently protrude the pharynx like a proboscis or tube, and not unfrequently has manducatory pincers, like as in Insects.

3254. On the head there are mostly annulate tentacula with muscular fibres, and frequently simple eyes.

3255. In those species which draw the water itself into the body and use it for the purposes of respiration, the formation of the mouth has risen higher, and the pharynx been provided with maxillæ, in number five or ten—Echini, Holothuriæ. These maxillæ form in themselves a peculiar skeleton around the pharynx, which is ranged circularly instead of by pairs.

3256. The nervous system is directed according to the relations of the tegument and intestine. It forms two ganglionic cords running along the ventral side of the body, and, where it makes with the nerves going to the maxillæ a ring around the pharynx, corresponds to the pharyngeal or pneumogastric nerves.

3257. In reference to the sense of feeling it may be said, that the Worms were those among the Sensitive animals, which feel by the whole tegument or body. Their body itself is a tentaculum.

3258. The sexual parts are likewise intestini-and dermiform, not glandular in figure like the ovarium and testis of Mussels and Snails, but tubular, as in the Entozoa. There are usually two oviducts and two seminal tubes to be found.

3259. So far as we are acquainted with the Red-blooded worms, they are androgynous, at least as regards the Earth-worms and Leeches, and their sexual parts are indeed tolerably symmetrical; yet they do not open posteriorly, but far forwards on the ventral side of the body, this being the case with even the male sex-organs.

Class 8. Branchial, Pedal Animals.

3260. The representation of the Cutaneous animals is not yet the entire completion of the tegument. It attains a higher grade by separating in accordance with the visceral systems, and in the conversion of the branchiæ into sensorial organs or feet.

The branchiæ endeavour to separate self-substantially, and form a body of their own. The branchial body is the thorax.

By this attempt, the abdomen originates "per se" as the body of the intestinal and sexual system. The branchiæ upon it are arrested or stunted. In like manner the body of the nerves separates itself from the thorax and becomes head.

But meanwhile this separation is only imperfect; the head and thorax, if otherwise distinguished by their size and the feet, are for the most part connate; abdomen and tail are usually fused together, and only to be recognized as distinct by the limbs or members.

With this greater division of the body each division of it obtains its articulation into rings; but they will be hardened by virtue of the separation of the branchial network, or will become horny—Horny animals.

3261. With the conversion into horny texture of the body, its branchial filaments or tentacula must undergo a similar change, and divide likewise into rings like the general or bodily tegument.

Annulate, horny branchial filaments, are feet—Pedal animals.

A part of the branchiæ remains hanging to the feet, mostly to their basal joints, and is supported by animal motor members or limbs; the respiration becomes voluntary—Branchial animals.

The Annulate animals, having branchiæ and feet, are the Crustacea or Crabs.

The branchiæ and feet are, of course, most largely developed upon the thorax.

Those upon the abdomen continue small, and those upon the tail or sexual body dwindle in size and change into other organs, such as fins, sacs, filaments, pincers.

3262. The number five of the branchiæ is also exhibited in the feet. There are mostly five large pairs of feet on the thorax, and as many small ones on the abdomen, as in the Crabs.

On the tail they appear more dwindled in size, and are frequently reduced to a smaller number.

Each part of the body has properly five rings; and these parts being the thorax, abdomen and tail, there are thus fifteen rings in all.

In the Crabs it is distinctly demonstrated that the maxillæ are nothing else but feet; there are therefore for the most part, after taking into account sundry arrests and coalescences, five pairs of maxillæ also.

The Crabs have usually two pairs of antennæ, whose signification is unknown; one pair is probably the elongation of the ear.

All Branchial animals have eyes, frequently too supported upon articulated pedicles.

They have a double nervous cord upon the ventral surface of the body.

They have, like the Mussels, a heart upon the dorsal aspect, and arteries with veins.

The intestine opens into the apex of the tail, and is surrounded by a liver.

The sexual parts still open for the most part on the thorax, and indeed by two orifices, as in the Worms.

There are no more androgynous or bisexual beings in the present class.

In some few the branchiæ already enter the body and become air-tubes, as in the Scolopendræ, Spiders and Scorpions.

The Branchial animals repeat, as being the second class of their circle, the Corals and Snails; their "quasi" coat of mail is therefore harder, often richer in calcareous ingredients, and, in addition to this, lies frequently upon the thorax or branchia as a special testa, called the scute or shield.

Class 9. Tracheal, Alary Animals.

Annulate animals, whose branchiæ have undergone a partial conversion into tracheæ and into wings, are the Insecta proper or Flies.

3263. A Worm with feet, tracheæ and wings, is an Entomon or Insect.

3264. The first separation takes place in respect to the three tegumental segments of the body, the abdomen, thorax, and head. All three are, in the Insects, more separated from each other than in the Branchial animals, and united together usually by a narrow tube; even in cases also, where they are connate with each other, they are still easily recognized by respect being had to size, form, or appendages.

Every Insect is divided into three segments. In the abdomen are the organs belonging to the Worm, such as the intestine, and a fatty body which appears to be an analogue of the liver, a dorsal vessel, tubular sexual parts and air-tubes (tracheæ), but nothing else.

The abdominal feet now disappear entirely, and even the number of thoracic feet diminishes, owing, doubtless, to the production of wings.

3265. The thorax alone is reserved for the limbs or locomotive members. It never carries more than three pairs of legs and two pairs of wings. Of the viscera, it contains nothing but the pharynx, while in the Crabs, important intestinal organs and even the liver, are situated within its cavity. It is in Insects therefore nothing else than a medium of support to the respiratory organs which have become limbs. Hence the thorax never has more than three rings, namely, one for each pair of legs. The wings invariably stand upon its two posterior rings.

3266. Since the limbs of the Insect are only the lateral filaments of the Worms, which have become hard and consequently hollow; they are as such not to be termed true feet, but are only to be compared with branchial arches or ribs; a step by which their greater number also admits of being understood. They are not to be compared with our feet, but unto the toes, which have been separated from each other as far as the rings of the body. The Crab has properly five thoracic and five abdominal toes. All its thoracic feet taken together are only equivalent to our hand.

The feet of the higher animals are only Insect-feet connate or coalesced.

3267. In other respects they already typify or prefigure true limbs, as well from their position as by the division of their joints. A perfect beetle's foot divides exactly like the limb of Man, into femur, patella, tibia, tarsus, and phalanges. These parts of the leg must not, however, be so absurdly divided and named, as has hitherto been unfortunately the case in our systems, where the femur has been called coxa, the patella trochanter, the tibia femur, while the toes have been lumped under the name of tarsus. (Ed. 1st, 1811. § 3087.) The regular number of the toes or tarsal joints is five, so that they correspond to our digital phalanges, to the metacarpal, and the anterior carpal bone.

3268. The wings are the branchiæ of the Mollusc that have been set free; they are placed therefore upon the back and are four in number. In many Insects there is still a pair of wing-like scales in front of the four wings, as in some Lepidoptera. They perhaps correspond to the shells of Molluscs, are branchial opercula.

It is only from this point of view that the structure of Insects admits of being fully understood; and apart from this it is absolutely devoid of all analogy. Thus it is possible for only six legs to take their origin from the thorax in the direction downwards, and nevertheless for there still to be wings upon the dorsum or back. The wings of Birds are by no means homologous to the alar appendages of Insects; they are, as is well known, the anterior members themselves, and there is no longer therefore in the Bird any feet attached to the thorax below, as in Insects. Besides, if the wings did not signify arms in the Bird, then it must have four legs. Thus in the Insect the wings could not also mean feet.

Their structure also speaks in favour of our view of the Insect's wings. They are known to be completely traversed by respiratory tubes, are true, or only desiccated, branchiæ—aerial gills. (Ed. 1st, 1811. § 3088.) Wings and feet are dependent from the same ring of the body, and are thus like the branchiæ and feet of the Crabs. Let the Crab's branchiæ elongate and dry, and they will thus be wings.

3269. Since the wings are newly eliminated organs of the sense of feeling, so are they here characteristic of the animal, and are consequently of greater importance for the purposes of division and arrangement than the organs of the head, which in all the lower animals is only an apparent head, and cannot therefore serve to characterize groups, &c.

3270. That the tracheæ in Insects have been developed out of the branchiæ by saccular inversion, is a fact displayed in a particularly distinct manner by the Scorpions and Spiders, who still possess at bottom internal branchial laminæ, unto which, however, air instead of water finds its way. It may be said, that with the general conversion into horny texture, the arteries of the Mussels were transmuted into internal tracheæ, and the branchial flabellæ into external organs. Would we interpret the body of the Insect in a strictly philosophic sense, the parts must then receive very different names to what they now bear. Properly speaking, in our own species the thorax has no limbs, but only the neck. The upper limbs are not lungs, but branchial organs, and it is the cervical vertebræ, from between which nerves are sent off to the arms, for it is just upon the neck also that the branchiæ have been left. What is termed therefore the thorax in Insects, would be properly their neck. Their abdomen would consist accordingly of thorax and abdomen, and it is this also, which carries on the principal share of the respiratory process. It therefore consists generally of ten rings, and has ten pairs of spiracula, namely, twice five, for both thorax and abdomen.

Or again, the abdomen may be regarded as an intestinal and sexual cavity, and the thorax may be left with its own name. In that case there would be five spiracles for the sex, five for the intestine, and perhaps only two for the thorax.

Would we proceed yet further; the head can then only be viewed as pharynx, and consequently as neck.

3271. In most Branchial animals that live in the water, a perfect circulation is present, because, by reason of their feeble amount of respiration, all the blood is not consumed. This is also the case in the young of air-breathing Insects, so long as they may have to grow. But when they have ceased to do this, so strong an amount of tension emerges in the circulation, owing to the increased respiration of air, that blood remains but in scanty quantity to be carried back by the veins, and the arteries now for the most part convey the air in a pure state, namely, uncombined with blood, as in the higher animals.

3272. As the air-tubes pass to all parts of the body, like the arteries whose place they now supply, so does the nutritive juice become everywhere oxydized and converted into parenchyma or tissue. The nutritive juice doubtless transudes at once through the intestine and penetrates to all parts, as in the Plants.

3273. Of the vascular system nothing at last remains but the dorsal vessel, whose ramifications appear to disappear entirely. According to its analogy with the Crabs, Scorpions, and Spiders, it is the aorta. It appears, as if in Insects the circulation dies off from the living body.

The whole Insect is an air-organ, an aero-vascular stem. All the organs respire directly, such as the intestine, the motor fibres, nerves, sexual parts, and wings. There is no part unto which tracheæ do not pass, and in this respect completely resemble the arteries of other animals.

3274. The intestine is invariably furnished with an anus, and that too situated quite posteriorly. It is usually expanded into several stomachs and has appendages, almost as in Fishes, which virtually correspond to the abdomino-salivary or pancreatic gland.

3275. The salivary ducts open into the mouth, and thus as in the Snails and Kracken, whose similar structures they repeat.

3276. Whether what have been called the biliary vessels are what the name implies, and really convey bile from the fatty body to the intestine, or whether they are lacteal vessels and discharge their fluid near the rectum into the dorsal vessel, does not yet admit of being determined. They have been thought to constitute an urinary apparatus; only certain cysts which occur in connexion with the sexual parts, appear rather to correspond to the latter.

3277. The nervous system consists, as in the Worms, of two ganglionic ventral chords.

3278. In the head, the feet again, and probably also wings, undergo repetition. This repetition is nowhere so distinct as in Insects. He who can still entertain any doubt of the maxillæ being arms, let him resolve to descend into the Insect-world, and he will become in place of a sceptic, a believer. (Ed. 1st, 1811. § 3095.) What have been called manducatory pincers move outwards as well as the legs, and seize like arms, are only arms. Their gripe takes place in the lateral or horizontal direction, and resembles that of scissors or shears.

3279. Where, moreover, there are three pairs of legs on the thorax, we find also three pairs of maxillæ, namely, an upper and lower maxilla, and a labium or inferior lip, which consists of the same parts as the maxillæ, only they are united by tegument.

3280. Where there are five or more pairs of legs on the thorax, as in the Crabs, there also are found as many pairs of maxillæ.

3281. Upon these maxillæ, palpi are likewise situated, which are probably nothing else than what has been termed tarsus, thus repeated in the head also. They are only arrested upon the upper maxillæ or mandibles. (Ed. 1st, 1811. § 3096.)

3282. The wings appear to be repeated upon the head as antennæ. Thus the head also is in the Insects a perfect trunk.

3283. Upon the head there is nothing more than the eyes. They have also become horny in texture, whereas before they were completely membranous, as in the Snails.

The eyes have been subordinated to the sense of feeling; they are nervous papillæ placed beneath a transparent tegument upon the apex of a tentaculum.

Insects therefore have a number of eyes; they stand either separate, as in the Worms, and are then called simple eyes, or they are crowded together, constituting compound eyes.

3284. Of the other sensorial organs a papilliform elevation in the pharynx is frequently exhibited as a tongue.

3285. Ears are found in the Crabs at the root or base of the antennæ, or in them there is only a tympanic cavity with an ossicle inclosed within; in the Insect there is nothing of the same kind. But meanwhile, since many species attract each other by means of sounds, they must thus possess the faculty of hearing. The antennæ therefore probably correspond to the auditory conch. The auditory conch of the Mammalia ranks also in the signification of the hand, and thus of the organ of feeling.

Nevertheless the antennæ may be transformations of the wings. The auditory ossicles are indeed members which have originated from branchiæ. Probably the antennæ are the auditory ossicles themselves which have emerged outwards, as in the Fishes and Reptiles.

There is no trace of a nose; nor can there be any, for it is the anterior orifice of the vertebral canal, and this is wanting in all lower animals. A noseless animal is an inferior or Tegumental animal.

3286. The sexes are separate, because they are Air-breathing animals and perfectly symmetrical in form. The ovi-and seminal ducts are likewise symmetric and in pairs. The ovipositors and penes are perfect, as in the Snails, because they can be shoved forwards, but not everted as in the latter.