Front matter (continued 4)

"It is visible that new strata have been successively formed by the same reiterated motion of the waters from the deposition of sediments and other constant causes from time immemorial; of which I find strong proofs in the different beds of fossils, shells, and other marine productions found in Roussillon near the village of Naffiac, about seven or eight leagues from the sea; these beds of shells which are inclined from the west to the east, and in different angles, are separated from each other by banks of sand and earth, are sometimes from one and a half to two or three feet in thickness. They appear as if sprinkled with salt in dry weather, and form together hillocks from twenty-five to thirty fathoms in height: now a long chain of hills of such an height can only be formed gradually, and at different successions of time. Such might be the effect of an universal deluge, which must have disturbed all nature; but which could not have given a regular form to these different beds of fossil shells, but would have jumbled them together without any order or regularity."

On this subject I am perfectly of the same opinion as M. Barrere, excepting as to the formation of mountains, which I cannot agree ought to be entirely attributed to the causes which occasion the ocean to gain upon the land on some parts, and lose it upon others. As I am, on the contrary, of opinion, I could produce many convincing arguments to prove that most of the eminencies seen on the surface of the earth have been actually formed in the sea itself. First, because they have a correspondence of saillant and returning angles, which necessarily implies the cause we have assigned, that is, the motion of the currents. Secondly, because downs and hills, which are formed by the materials that the sea brings on its shores, are not composed of marble and hard stone, like common hills; the shells also in the former are generally only fossils, whereas in the latter, the petrifaction is compleat; besides the beds of earth are not so horizontal in downs as in the hills composed of marble and hard stone, but are more or less inclined, as in the hills of Naffiac, whereas in the hills and mountains, formed under the water by the sediment of the sea, the strata are always parallel, and very often horizontal, and the shells and other marble are entirely petrified. I have no doubt of proving that marble and other calcinable matters, which are almost all composed of madrepores, astroites, and shells, have acquired their hardness and perfection at the bottom of the sea; on the contrary, gravel, soft stones, incrustations, stalactites, &c. which are also calcinable and found in the earth, and formed since our continent has been discovered, cannot acquire this degree of hardness and petrifaction which marble or hard stones have.

In the history of the French Academy for 1708, may be seen the observations of Saulmon, on the subject of the galets found in many places. These galets are round and flat flints very smooth, and which are cast on the shores by the sea. At Bayeux, and at Prutel, which are a league from the sea, we find them in digging wells or pits. The mountains of Bonneuil, Broie, and Quesny, which are eighteen leagues from the sea, are all covered with galets; they are also found in the valley of Clermont in Beauvois. M. Saulmon likewise relates, that a hole, 16 feet deep, was bored horizontally into the beach of Tresport, which is soft earth, and that it entirely disappeared in 30 years: so that if the sea always encroaches alike, it would gain half a league in 12,000 years.

The motions of the sea are therefore the principal causes of the alterations which have happened, and which daily happen on the surface of the globe. But there are many, other causes, which, though less considerable, contribute to those changes. Running waters, rivers, streams, the melting of snow, torrents, frosts, &c. have occasioned many changes; the rains have diminished the height of mountains; rivers and rivulets have raised plains, and stopped up the sea at their mouths; the melting of snow, and torrents, have dug hollows in vallies; and the frosts have split rocks and separated them from their former stations. We might quote an infinity of examples on the alterations these causes have occasioned. Varenius says, that rivers convey into the sea great quantities of earth, which they deposit at a greater or less distance from the coasts, according to the rapidity of their currents; these earths fall to the bottom of the sea, and, at first, form those small banks which daily encrease, become shoals, and, at last, form islands, which are fertile and inhabitable. This is the manner in which the islands of the Nile are formed, as well as those of St. Laurence, the Isle of Landa, situate on the coast of Africa, near the mouth of the river Coanza, the island of Norway, &c.[AZ] To these may be added the island of Trong Ming, at China, which has been gradually formed by the earth that the river Nankin has brought and deposited it at its mouth. This island is more than 20 leagues long by five or six broad.[BA]

The Po, Trento, Athesis, and other rivers of Italy, bring with them great quantities of earths into the lakes of Venice, especially during the time of inundations, which, in course of time, must fill them up. In many places they are now dry at low water, and, excepting the canals, which are kept up at a great expence, have no depth of water.

At the mouths of the Nile, the Ganges, the Indus, the Plata, the Nankin, and of many other rivers, the earth and sand deposited form considerable banks. Loubere, in his Voyage to Siam, says, that the banks of sand and earth daily increase at the mouths of the great rivers of Asia, insomuch that the navigation of them becomes every day more difficult, and will one day be impassable. The same remark may be made of the large rivers of Europe, and particularly of the Wolga, which has more than 70 mouths in the Caspian sea, and of the Danube, which has seven in the Black sea, &c.

As it seldom rains in Egypt the regular inundations of the Nile proceed from the torrents which fall therein from Ethiopa. These annually bring with them great quantities of mud, which they not only deposit on the land of Egypt but even throw to a considerable distance in the sea, and thus lay the foundation of a new land, which, in the course of time, arises therefrom; for, by sounding with the lead, we find, at more than 20 leagues distance from the coast, the mud of the Nile at the bottom of the sea, and which is every year increasing. Lower Egypt, where[BB] Dela at present stands, was formerly a gulph of the sea. Homer tells us that the island of Pharos was 24 hours voyage from Egypt, and at present it is almost contiguous to it. The soil of Egypt has not the same depth of good ground throughout its extent, it lessens as we approach the sea. Near the borders of the Nile there is sometimes near thirty feet depth of good earth, whereas at the extremity of the inundation there is scarcely more than seven inches.[BC] The town of Damietta, at present more than 10 miles from the sea, in 1243 was a sea-port. The town of Fooah, which, 300 years ago, was situate at the mouth of the Canopic, a branch of the Nile, is now more than seven leagues from it. Within 40 years the sea has retreated half a league from before Rosetta and Idern.

The great rivers of America, and even those which have been but lately discovered, have suffered great alterations at their mouths. Charlevoix, speaking of the river Mississipi, says, that at its mouth, below New Orleans, the country forms a point of land which does not appear to be very ancient, for by digging but a little into the earth water is met with; besides, the quantity of small islands which have recently been formed at all the mouths of this river, leaves no doubt of this neck of land being formed after the same manner. It appears certain, says he, that when M. de la Salle went down the Mississipi, to the sea, the mouth of this river was not as it is at this present time.

"The nearer we approach towards the sea, adds he, the more it becomes perceptible, the bar has scarcely any water in most of the small outlets which the river has opened, and which have multiplied so greatly from the trees that are carried along with the currents, one of which stopt in a part where it is shallow, will entangle hundreds. I have seen, continues he, 200 leagues from New Orleans, collections of trees, one of which would have filled all the timber-yards of Paris. Nothing can set them free; the mud which the river brings down serves to cement, and, by degrees, covers them. Each inundation leaves a new stratum, and, after 10 years, shrubs and vegetables grow thereon: after this manner most points and islands are formed, which so often change the course of rivers."[BD]

Nevertheless all the changes which rivers cause are very slow, and become not considerable till after a long series of years: but quick and sudden changes have happened by inundations and earthquakes. The ancient Egyptian priests, 600 years before the birth of Christ, asserted, according to the Timæus of Plato, that there was a great island near Hercules Pillars; called Atlantis, which was larger than Lybia and Asia taken together; and that this island was buried under the waters of the ocean after a great earthquake. "Traditur Atheniensis civitas restitisse olim innumeris hostium copiis quæ, ex Atlantico mari profectæ, prope cunctam Europam Asiamque obsederunt; tunc enim fretum illud navigabile habens in ore et quasi vestibulo ejus insulam quam Herculis columnas cognominant; ferturque insula illa Lybiâ simul et Asiâ Major fuisse, per quam ad alias proximas insulas patebat aditus, atque ex insulis ad omnem continentem è conspectu jacentem vero mari vicinam: sed intrà os ipsum portes augusto sinu traditur, pelagus illud verum mare, terra quoque illa verè erat continens, &c. Post hæc ingenti terræ motu jugique diei unius et noctis illuvione factum est, ut terra dehiscens omnis illos bellicosos absorberet, et Atlantis insula sub vasto gurgite mergeretur." Plato in Timæus. This ancient tradition is not absolutely contrary to all probability. The earths which were absorbed by the waters are perhaps those which join Ireland to the Azores, and those to the continent of America; for in Ireland there are the same fossils, shells, and marine productions as in America, some of which are different from any found in other parts of Europe,

Eusebius relates two testimonies on the subject of deluges: one of which is Melo, who says that the plains of Syria had formerly been laid under water; the other is Abydenus, who says, that in the time of King Sisithrus there was a great deluge, which had been predicted by Saturnus, Plutarch De Solestia Animalium. Ovid, and other mythologists, speak of the deluge of Deucalion, which, according to them, was in Thessaly, about 700 years from the universal deluge. It is also asserted that there had been one more ancient in Attica, in the time of Ogiges, about 230 years before that of Deucalion.

In the year 1095 there was a deluge in Syria, which drowned a number of people.[BE] In 1164 there was so considerable a one in Friezeland, that all maritime coasts were covered, and several thousands of the inhabitants drowned.[BF] In 1218 there was another inundation which destroyed near an hundred thousand people. There are a multitude of other examples of great inundations, like that of 1604 in England, and many more.

A third cause of the change on the surface of the globe, are impetuous winds. They not only form downs and hills on the sea shores, but they often stop and choak up rivers, and change their directions; they tear up cultivated land, destroy trees, overthrow edifices, and cover entire countries with sand. We have an example of these inundations of sand on the coasts of Britany in France: the history of the Royal Academy at Paris, anno 1722, makes mention of it in the following terms.

"In the environs of St. Paul de Leon, in Lower Britany, there is a quarter near the sea, which before the year 1666, was inhabited; but is so no longer, by reason of a sand which covers it to the height of more than twenty feet, and which gains ground every year. Reckoning from that time it has proceeded upwards of six leagues into the country, and is now not more than about half a league from St. Paul, so that according to all appearance that town must soon be deserted. The tops of some steeples and chimnies are still seen peeping out of this sea of sand; the inhabitants of the interred villages have always had sufficient time to quit their houses in safety.

"An east or north wind increases this calamity, by raising up a sand of a very fine nature, which sweeps it away in such great quantities, and with such velocity, that M. Deslandes, to whom the academy are indebted for this observation, when walking in that country during an east wind, was obliged, from time to time, to wipe it off his hat and cloaths they were so loaded with sand, and felt so heavy. Besides, when this wind is violent, it throws this sand over a small arm of the sea into Roscof, a small port much frequented by foreign vessels; the sand collects in their streets to the height of two feet, and the inhabitants are obliged to have it carted away. There are many ferruginous particles in this sand, which are easily discovered by a magnet.

"The coast which furnishes this sand extends from St. Paul as far as Plouefoat, somewhat more than four leagues. The disposition of the place is such that only the east or the north-east wind can convey the sand over the lands. It is easy to be conceived how the sand, conveyed and accumulated by the wind in one part, can again be taken up by the same wind and carried farther, and that the sand can thus advance into and cover the country while the mine which furnishes it continues unexhausted; for without this the sand, by advancing, would always diminish in height, and would cease its destructive ravages. Now it is but too possible that the sea throws up or deposits new sand in the place from whence the wind raises it up, and therefore the dreadful effects may long continue.

"The disaster is but of modern date, possibly the shoal which furnishes it has not yet a sufficient quantity to lift itself above the surface of the sea, or perhaps the sea has but just left it uncovered. There has been some alteration on the coast, and the sea at present reaches, at high water, half a league beyond certain rocks that formerly it never passed.

"This unhappy province justifies what the ancient and modern travellers relate concerning the tempests of sand in the deserts of Arabia, in which cities and armies have been enveloped and destroyed."

Mr. Shaw tells us that the ports of Laodicea, Jebila, Tortosa, Rowada, Tripoli, Tyre, Acra, and Jaffa, are all filled up with sand brought thither by the great waves which beat on that side of the Mediterranean when the west wind blows impetuously.[BG]

It is useless to give a greater number of examples of the alterations that have happened on the surface of the globe. Fire, air, and water, produce continual changes, which become very considerable by time. It is not from general causes alone, whose effects are periodical and regular, that the sea successively takes the place of the earth, and forsakes its own dominions. There are a number of particular causes which contribute to these mutations, such as earthquakes, inundations, sinking of mountains, &c. Thus the most solid thing, at least to our conception, like the rest of nature, undergoes continual and perpetual vicissitudes.

CONCLUSION

OF THE

THEORY OF THE EARTH.

By the proofs we have given in Articles VII. and VIII. it appears certain that the whole of the present dry land was formerly covered by the sea. It appears also as certain, from Article XII. that the flux and reflux, and other motions of the ocean, continually detach, from the side and the bottom of the sea, shells and matters of every kind, some part of which are deposited in other places in form of sediments, and which are the origin of the parallel and horizontal strata every where to be met with. We have proved in Article IX. that the inequalities of the globe have been caused by the motion of the sea, and that mountains have been produced by the successive masses and heapings of the sediments we have just described. It is evident by Article XIII. that the currents, which at first followed the direction of these inequalities, afterwards gave to them all the figure which they at present preserve; that is, that alternate correspondence of the saliant angles always opposed to the returning angles. It appears likewise by Articles VIII. and XVIII. that the greatest part of the matters which the sea has detached from its sides and bottom were, when deposited as sediments, in form of a fine impalpable powder, which perfectly filled the cavities of the shells, whether it was of the same nature or only analogous to that with which they were composed. It is certain, from Article XVII. that the horizontal strata which have been produced by the accumulation of sediments, and which at first were in a soft state, acquired hardness in proportion as they became dry, and that this drying has produced perpendicular clefts, which cross the horizontal strata.

It is impossible to doubt, after perusing the facts in the Articles X. XI. XIV. XV. XVI. XVII. XVIII. and XIX. that an infinite number of revolutions, particular changes and alterations, have happened on the surface of the globe, as well from the natural motion of the waters of the sea as by the effects of rain, frost, running waters, winds, subterraneous fires, earthquakes, inundations, &c. and that consequently the sea has alternately changed places with the earth, especially in the earliest times after the creation, when the terrestrial matters were much softer than they are at present. It must nevertheless be acknowledged, that we can but very, imperfectly judge of the succession of natural revolutions; that we can still less judge of the cause of accidents, changes, and alterations; that the defect of historical monuments deprives us of the knowledge of particular facts, and experience and time is deficient to us. We do not pay any consideration that, though the time of our existence is very limited, nature proceeds in her regular course. We would condense into our momentary existence the transactions of ages past and to come, without reflecting that this instant of time, nay even human life itself, is only a single fact in the history of the acts of the Almighty.

HISTORY OF ANIMALS.

CHAPTER I.

A COMPARISON BETWEEN ANIMALS, VEGETABLES, AND OTHER PRODUCTIONS OF NATURE.

Amidst the infinite number of objects that offer themselves to our view, and with which the surface of the earth is every where covered, Animals hold the first rank both on account of their formation, and their evident superiority over vegetables and other matters. Animals, by their senses, form, motion, and many other properties, have a more intimate connection with those things which surround them than vegetables; and the latter, by their figure, growth, and variety of component parts, have also a nearer relation with external objects, than either minerals or stones, which have not any kind of life or motion. By this number of properties it is, that the animal claims pre-eminence over the vegetable, and the vegetable over the mineral. Man, to consider him by his material form alone, is only superior to the brute creation by possessing some few peculiar properties, such as those given to him by his tongue and hands; and although the works of the Creator are in themselves equally perfect, the animal, according to our mode of perception, is the most complete, and man the most perfect animal.

What variety of springs, what forces, and what mechanical motions are enclosed in this small part of matter which composes the body of an animal? What properties, what harmony, and what correspondence between the various parts? How many combinations, arrangements, causes, effects, and principles, conspire to complete one end, and which we know only to be results so very difficult to comprehend, that they only cease from being marvellous by the long custom of not reflecting on them?

Nevertheless, however admirable this work appears, it is not the individual that is the most wonderful; but it is in the succession, reproduction, and duration of species, that nature becomes inconceivable. This faculty of reproduction, which resides alone in animals and vegetables; this kind of unity always subsisting, and seemingly eternal; this procreative power, which perpetually exercises itself without being destroyed, is a mystery, the depth of which we are not enabled to fathom.

Inanimate bodies, even the stones and dirt under our feet, have some properties; their existence alone supposes a great number; and the least organic matter has an infinity of relations with the other parts of the universe. We shall not say, with some philosophers, that matter, under whatever form it may be, is sensible of its existence and relative faculties. This is a metaphysical question, and of which we do not here propose to treat, it will be sufficient to observe, that not having a perfect knowledge of our own relation with external objects, we cannot doubt that inanimate matters are still more ignorant; besides, as our sensations do not in the least resemble the objects which cause them, we must conclude, by analogy, that inanimate matter has neither sentiment, sensation, nor a consciousness of its existence; to attribute any of these faculties to it, would be giving it the power of thought, action, and perception, nearly in the same manner as we think, act, and feel, which is as much repugnant to reason as it is to religion.

Inanimate bodies being formed of earth and dust, we have, of course, some properties in common with them, but they are merely relative to what arises from general matter, such as extent, impenetrability, weight, &c. but as these properties, purely material, make no impression of themselves, as they exist entirely independent, and do not at all affect us, we cannot consider them as a part of our being; it is therefore the organization, the soul, and the life, which constitute our existence. Matter, considered in this light, is less the principal than the accessor. It is a foreign expansion, the union of which is unknown, and the presence hurtful to us; and thought, which is the constituent principle of our being, is very probably entirely independent.

We exist, therefore, without knowing how, and we think without knowing why; but whatever is the manner of our being or thinking, whether our sensations are true or false, the result of them are not less certain. This order of ideas, this train of thoughts, which internally exist from ourselves, although very different from the objects that cause them, give rise to the most real affections, and occasion relations with external objects, which we may consider as real affinities, since they are invariable, and always the same. The human species, therefore, may be said to hold the first rank in the order of nature, the brute creation the second, vegetables the third, and minerals the last; for although we cannot clearly distinguish between our animal and spiritual qualities, and although the brute creation are endowed with the same senses, possess the same principles of life and motion, and perform a number of actions like man, yet they have not the relation with external objects in the same extensive manner we have, and consequently the resemblance must fail in various respects. The distance is greater between man and vegetables, and still more so from minerals, as vegetables possess a degree of animation, while minerals are destitute of every principle that tends to organization.

To compose, therefore, the history of an animal, we must first nicely inspect into the general order of his particular relations, and afterwards distinguish those he has in common with vegetables and minerals. An animal has nothing in common with a mineral, excepting general properties of matter; his nature and œconomy are totally different: the mineral is a mere senseless and inactive matter, without organization, faculties, or power of reproduction; a dead mass, fit only to be trod under foot by man and animals; even the most precious metals are thus considered by the philosopher, as they possess but an arbitrary value, subordinate to the will, and dependent on the convention of men.

In an animal all the powers of nature are united; the properties by which it is animated are peculiar to it; by its senses it can will, act, determine, and communicate with the most distant objects: its body is a centre, to which every thing is connected; a point where the whole universe is reflected; a world in miniature. These are the properties which peculiarly belong to it; those which it possesses in common with vegetables are the faculties of growth, expansion, reproduction, and increase.

The most apparent difference between animals and vegetables seems to be the faculty of moving from place to place, which animals are endowed with and vegetables not. It is true we are not acquainted with any vegetable that has a single progressive motion; and there are many kinds of animals, as oysters, &c. to which this motion seems to have been denied; the distinction, therefore, is neither general nor necessary.

A more essential difference might be drawn from the faculty of sensation; but sensation includes such a variety of ideas, that we ought not to mention the word without giving some explication; for if by sensation we understand only a motion, occasioned by a check or resistance, we shall find the sensitive-plant is also possessed of it; if, on the contrary, we would have it signify to apprehend and compare ideas, we are not certain that brute animals possess it; if it is allowed to dogs, elephants, &c. whose actions seem to result from the same causes as those of men, it must be denied to an infinite number of others, especially to those which seem to be motionless. If we could give to oysters, for example, the same faculty of sensation as to dogs, though in an inferior degree, why should we not allow it to vegetables in a still lesser degree? This difference between animals and vegetables is not, therefore, general, nor well decided.

A third difference seems to arise from their method of feeding. Animals, by the means of certain external organs, seize those things which are agreeable to them: they seek their pasture and chuse their food. Plants are reduced to the necessity of receiving such nutriment as the earth furnishes: they have no diversity in the manner of procuring it; no choice in the kind, but the humidity of the earth is their only aliment; nevertheless, if we attend to the organization and action of roots and leaves, we shall presently discover that there are in those parts external organs, which vegetables make use of to obtain their food; that the root avoids and turns from an obstacle, or vein of bad earth, to seek for one that is better; that they divide their fibres, and even go so far as to change their form to procure nutriment for the plant. The difference between animals and vegetables cannot, therefore, be established on the manner in which they receive their nutriment.

This investigation induces us to conclude that there is no absolute essential and general difference between animals and vegetables, but that nature descends, by degrees imperceptibly from an animal which is the most perfect, to that which is the least, and from the latter to the vegetable. The water polypus may therefore be considered as the line where the animal creation ends and that of plants begin.

If, after having examined the distinctions, we search after the resemblances between animals and vegetables, we shall find the power of reproduction is general, and very essential to both; a faculty which would almost lead us to suppose that animals and vegetables are nearly of the same order of beings.

A second resemblance may be drawn from the expansion of their parts, a property which is common to both; for vegetables grow as well as animals, and if the manner in which they expand is different, it is not totally nor essentially so, since there are very considerable parts in animals, as the bones, the hair, the nails, the horns, &c. whose expansion is a perfect and real vegetation; and the fœtus, at its first formation, may be said rather to vegetate than live.

A third resemblance arises from there being some animals which propagate like plants, and by the same method. The multiplication of the vine-fretter, which is made without copulation, is like that of plants by seeds; and that of polypuses, by cutting them, resembles the multiplication of trees by slips.

We can then assert with greater foundation, that animals and vegetables are beings of the same order, and that nature passes from one to the other by insensible links; since the properties wherein they resemble each other are general and essential, and those on which they differ confined and particular.

If we compare animals and vegetables by other lights, for example, by number, situation, size, form, &c. we shall draw fresh inductions from them.

The number of the animal species is much greater than that of plants. In the class of insects alone there are a greater number of species than there are kinds of plants on the surface of the earth. Animals likewise much less resemble each other than plants; and it is this resemblance among the latter which makes the difficulty of knowing and discerning them, and has given rise to so many botanical systems; and it is for this reason that more labour has been bestowed on that than on zoology.

Besides, there is another advantage of knowing the species of animals, and distinguishing them one from another, which is by regarding those as one and the same species, who, by means of copulation, produce and perpetuate beings like themselves; and as a different species, those from a connection between whom nothing is produced, or whose product are unlike their parents. Thus a fox will be a different species from a dog, if nothing results from a copulation of a male and female of these two animals, and when even there should result a bipartite animal, or a kind of mule, which cannot generate, that will be sufficient to establish the fox and dog of two different species. There is not the same advantage to be had in plants, for although some have pretended to discover sexes, and although divisions of breeds have been established by the parts of fecundation; yet, as these distinctions neither are so certain, nor so apparent as in animals, and the production of plants is made in many modes, that the sex has no part in, and where the parts of fecundation are not necessary, this idea cannot be made use of with any success; it is only on a misapprehended analogy that this sexual method has been pretended to distinguish all the different species of plants.

Notwithstanding the number of animals is greater than that of plants, yet that is not the case with respect to the number of individuals in each species. In animals as well as in plants, the number of individuals is much greater in the small species than in the large. Flies are, perhaps, a million times more numerous than elephants; so likewise there are more kinds of plants than trees; but, if we compare the quantity of individuals in each species, we shall find that the plant is more abundant than the animal; for example, quadrupeds bring forth but a small number of young, and at considerable distances of time; trees, on the contrary, produce every year, a great quantity. It may be said that this comparison is not exact, and to render it so, we should compare the quantity of seeds produced by a tree, with a quantity of germs contained in the semen of an animal, and then, perhaps, we should find, that animals are still more abundant in their seed than vegetables. But it should be considered that it is possible by collecting and sowing all the seeds of an elm, for instance, that we might have 100,000 young ones from the product of a single year; and that should we supply a horse with as many mares as he could cover in one year, there would be a great difference between the production of the animal and that of the vegetable. I shall not examine into the quantity of germs; first, because we are not acquainted with it in the animal creation: and secondly, because possibly there is the same number of seminal shoots in the vegetable: for the seed of a vegetable is not a germ, being as perfect a production as the fœtus of an animal, and to which, like that, a greater expansion is only wanting.

To my comparison may likewise be opposed the prodigious multiplication of certain kinds of insects: as the bee in particular, one of which will produce thirty or forty thousand. But it must be observed, that I speak in general of animals compared with vegetables; and besides, this example of bees, which perhaps is the greatest multiplication among animals, does not constitute a proof against what we have observed; for of thirty or forty thousand flies produced by the female bee, there is but few females; fifteen hundred, or two thousand males, and all the rest moles, or rather neutral flies, without sex, and incapable of procreating.

It must be owned, that in insects, fish, and shell-fish, there are species which seem to be very abundant; oysters, herrings, fleas, beetles, &c. are perhaps in as great numbers as mosses and the most common plants; but on the whole, the greatest number of the animal species is less abundant than the vegetable; and by comparing different kinds of plants with each other, there is not found such great differences in the number, as in the animal species; some of which bring forth a prodigious number, and others only a few; whereas the number of productions in plants is always very great throughout.

By what we have observed, it appears that the smallest and basest species seem to be the most prolific: the most minute are the most plentiful as well in animals as in plants, and in proportion as the animals are more perfect, they appear to decrease in number of individuals. Can it be thought, that certain forms of the body, as those of quadrupeds and birds, requisite for the perfection of sensation, would cost nature more organic particles than the production of less important animals?

Let us now pass to the comparison of animals and vegetables, with respect to situation, form, and size. The earth is the only place wherein vegetables can subsist. The greatest number grow above the surface, and are attached to the soil by roots. Some, as truffles, are entirely covered with earth, and a few grow under the water, but all require the surface of the earth to exist upon. Animals, on the contrary, are more generally dispersed; some dwell on the surface, and others in the bowels of the earth; some live at the bottom, and others swim in the waters of the ocean: some exist in the air, others dwell in the internal parts of plants, on the bodies of men and other animals, liquors, and even stones are not without them.

By the use of the microscope, a great number of new species of animals have been discovered: but singular as it may appear, we have not found more than one or two new species of plants by the help of this instrument. The small moss is, perhaps, the only microscopical plant spoken of; and we might, therefore, imagine that nature refused to produce very small plants, while she formed animalcules with profusion; but we might deceive ourselves by adopting this opinion without examination, and our error might arise from plants, in fact, resembling each other more than animals; so that this moldiness, which we only take for a very minute moss, may possibly be a kind of forest or garden, filled with abundance of various plants, although we are unable to mark the difference.

By comparing the size of animals and plants there will be found a great inequality, for the distance is much greater between the size of a whale and one of these microscope animals, than between the highest oak and the moss we are now speaking of. Although bulk be only a relative attribute, it may, nevertheless, be useful to inspect into the extreme boundaries nature has allotted to her productions. In bigness animals and plants seem to have a near equality; a large whale and a large tree forms a volume not very different; whereas, among the small it has been asserted there are animals so very minute that a million of them united together, would not equal, in size, the smallest moss-plant ever seen.

The most general and most sensible difference between animals and vegetables is that of figure, for the form of animals, although infinitely varied, has not any resemblance to that of plants; and although the polypus will, like plants, reproduce by cutting, and may be regarded as the link between the animal and vegetable kingdoms, not only by the mode of their reproduction but also by their external form, nevertheless the figure of the animal is so different from the external form of a plant that it is difficult to be deceived therein. Some animals form things resembling plants or flowers, but plants never produce any thing like an animal; and those admirable insects which produce and form the coral, would not have been taken for flowers if coral had not been regarded as a plant. Thus the errors wherein we might fall, by comparing plants with animals, will never have any influence but on a few objects which compose the link between both, and the more observations we shall make the more we shall be convinced that the Creator has not placed a fixed line between animals and vegetables; that these two species of organized beings have many more common properties than real differences; that the production of an animal does not require of nature more, and possibly, less exertion than that of a vegetable; that in general the production of organized beings does not require exertion, and that, in short, the living animated nature, instead of composing a metaphysical degree of beings, is a physical property, common to all matter.

CHAPTER II.

OR [BH]REPRODUCTION IN GENERAL.

We shall now make a more minute inspection into this common property of animal and vegetable nature; this power of producing its resemblance; this chain of successive individuals, which constitutes the real existence of the species; and without attaching ourselves to the generation of man, or to that of any particular kind of animal, let us inspect the phenomenas of reproduction in general, let us collect facts, and enumerate the different methods nature makes use of to renew organized beings. The first, and as we think the most simple method, is, to collect in one body an infinite number of resembling organic bodies, and so to compose its substance, that there is not a part of it which does not contain a germ of the same species, and which consequently of itself might become a whole, resembling that of which it constitutes a part. This preparation seems to suppose a prodigious waste, and to carry with it profusion; yet it is a very common munificence of nature, and which manifests itself even in the most common and inferior kinds, such as worms, polypuses, elms, willows, gooseberry-trees, and many other plants and insects, each part of which contains a whole, and by the single effect of expansion alone may become a plant, or an insect. By considering organized beings in this point of view, an individual is a whole, uniformly organized in all its parts; a compound of an infinity of resembling figures and similar parts, an assemblage of germs, or small individuals of the same kind, which can expand in the same mode according to circumstances, and form new bodies, composed like those from whence they proceed.

By examining this idea thoroughly, we shall discover a connection between animals, vegetables, and minerals, which we could not expect. Salts, and some other minerals, are composed of parts resembling each other, and to all that composes them; a grain of salt is a cube, composed of an infinity of smaller cubes, which we may easily perceive by a microscope; these are also composed of other cubes still smaller, as may be perceived with a better microscope; and we cannot doubt, but that the primitive and constituting particles of this salt are likewise cubes so exceedingly minute as to escape our sight, and our imagination. Animals and plants which can multiply by all their parts, are organized bodies, of which the primitive and constituting parts are also organic and similar, of which we discern the aggregate quantity, but cannot perceive the primitive parts only by reason and analogy.

This leads us to believe that there is an infinity of organic particles actually existing and living in nature, the substance of which is the same with that of organized bodies. As we have just observed, in a structure of a similar kind, though of inanimate matter, that it was composed of an infinity of particles which have a perfect semblance to the whole body, and as there must perhaps be millions of small cubes of accumulated salts to form a sensible individual grain of sea-salt, so likewise millions of organic particles, like the whole, are required to form one out of that multiplicity of germs contained in an elm, or a polypus; and as we must separate, bruise, and dissolve a cube of sea-salt to perceive, by means of crystallization, the small cubes of which it is composed; we must likewise separate the parts of an elm or polypus to discover, by means of vegetation and expansion, the small elms or polypuses contained in those parts.

The difficulty of giving way to this idea arises from a prejudice strongly established, that there is no method of judging of the complex, except by the simple, and that, to conceive the organic constitution of a body we must reduce it to its simple and unorganized parts, and that it is more easy to conceive how a cube is composed of other cubes than how one polypus is composed of others; but if we attentively examine what is meant by simple and complex, we shall then find that in this, as in every thing else, the plan of nature is quite different from the very rough draught of it formed by our ideas.

Our senses, as is well known, do not furnish us with exact representations of external objects, insomuch that if we are desirous of estimating, judging, comparing, measuring, &c. we are obliged to have recourse to foreign assistance, to rules, principles, instruments, &c. All these helps are the works of human knowledge, and partake more or less of the abstraction of our ideas; this abstraction, therefore, is what is called the simple, and the difficulty of reducing them to this abstraction, the complex. Extent, for example, being a general and abstracted property from nature, is not very complex; nevertheless, to form a judgment of it, we have supposed extents without depth, without breadth, and even points without any extent at all. All these abstractions have been invented for the support of our judgment, and the few definitions made use of in geometry have occasioned a variety of prejudices and false conclusions. All that can be reduced by these definitions are termed simple, and all that cannot be readily reduced are called complex; from hence a triangle, a square, a circle, a cube, &c. are simple subjects, as well as all curves, whose geometrical laws we are acquainted with; but all that we cannot reduce by these abstracted figures and laws are complex. We do not consider that these geometrical figures exist only in our imagination; that they are not to be found in nature, or, at least, if they are discoverable there, it is because she exhibits every possible form, and that it is more difficult and rare to find simple figures of an equilateral pyramid, or an exact cube in nature, than compounded forms of a plant or an animal. In everything, therefore, we take the abstract for the simple, and the real for the complex. In Nature, on the contrary, the abstract has no existence, every thing is compounded; we shall never, of course, penetrate into the intimate structure of bodies: we cannot, therefore, pronounce on what is complex in a greater or lesser degree, excepting by the greater or lesser each subject has to ourselves and to the rest of the universe; from which reason it is we judge that the animal is more compounded than the vegetable, and the vegetable more than the mineral. This notion is just with relation to us, but we know not, in reality, whether the animal, vegetable, or mineral, is the most simple or complex; and we are ignorant whether a globule, or a cube, is more indebted for an exertion of nature, than a seed or an organic particle. If we would form conjectures on this subject, we might suppose that the most common and numerous things are the most simple but then animals would be the most simple, since the number of their kind far exceeds that of plants or minerals.

But without taking up more time on this discussion, it is sufficient to have shewn that the opinions we commonly have of the simple and complex are ideas of abstraction, that they cannot be applied to the compound productions of nature, and that when we attempt to reduce every being to elements of a regular figure, or to prismatic, cubical, or globular particles, we substitute our own imaginations in the place of realities; that the forms of the constituting particles of different bodies are absolutely unknown to us, and that, consequently, we can suppose, that an organized body is composed of organic particles, as well as that a cube is composed of other cubes.

We have no other rule to judge by than experience. We perceive that a cube of sea-salt is composed of other cubes, and that an elm consists of other smaller elms, because, by taking an end of a branch, or root, or a piece of the wood separated from the trunk, or a seed, they will alike produce a new tree. It is the same with respect to polypuses, and some other kinds of animals, which we can multiply by cutting off, and separating any of the different parts;[BI] and since our rule for judging in both is the same, why should we judge differently of them?

It therefore appears very probable, by the above reasons, that there really exists in nature a number of small organized beings, alike, in every respect, to the large organized bodies seen in the world; that these small organized beings are composed of living organic particles, which are common to animals and vegetables, and are their primitive and incompatible particles, that the assemblage of these particles form an animal or plant, and consequently that reproduction, or generation, is only a change of form made by the addition of these resembling parts alone, and that death or dissolution is nothing more than a separation of the same particles. Of the truth of this we apprehend there will not remain a doubt, after reading the proofs we shall give in the following chapters. Besides, if we reflect on the manner in which trees grow, and consider how so considerable a volume can arise from so small an origin, we shall be convinced that it proceeds from the simple addition of small resembling organized particles. A grain produces a young tree, which it contained in miniature. At the summit of this small tree a bud is formed, which contains the young tree for the succeeding year, and this bud is an organic part, resembling the young tree of the first year's growth. A similar bud appears the second year, containing a tree for the third; and thus, successively, as long as the tree continues growing, at the extremity of each branch new buds will form, containing young trees like that of the first year. Thus it is evident, that trees are composed of small organized bodies, similar to themselves, and that the whole individual is formed by the union of small resembling individuals.

But, it may be asked, were not all these organized bodies contained in the seed, and may not the order of their expansion be traced from that source, for the bud which first appeared was evidently surmounted by another similar bud, which was not expanded till the second year, and soon to the third; and consequently the seed may be said really to contain all the buds, or young trees that would be produced for a hundred years, or till the dissolution of the tree itself? This seed it is also plain not only contained all the small organized bodies which one day must constitute the individual tree, but also every seed, every individual, and every succession of seeds and individuals, to the total destruction of the species.

This is the principal difficulty, and we shall examine it with the strictest attention. It is certain that the seed produces by the single expansion of the bud, or germ, it contains, a young tree the first year, and that this tree existed in miniature in that bud, but it is not equally certain that the bud of the second year, and those of the succeeding, were all contained in the first seed, no more than that every organized body and seed, which must succeed to the end of the world, or to the destruction of the species, were so. This opinion supposes a progress to infinity, and forms, of each individual, a source of eternal generations. The first seed, in that case, must have contained every plant of its kind which have existed or ever will exist; and the first man must actually and individually have contained in his loins every man which has or will appear on the face of the earth. Each seed, and each animal, agreeable to this opinion, must have possessed within an infinite posterity. But the more we suffer ourselves to wander into these kind of reasonings, the more we lose the sight of truth in the labyrinth of infinity; and instead of clearing up and solving the question, we confuse and involve it in more obscurity; it is placing the object out of sight, and afterwards saying it is impossible to see it.

Let us investigate a little these ideas of infinite progression and expansion. From whence do they arise? What do they represent? The ideas of infinity can only spring from an idea of that which is limited, for it is in that manner we have an idea of an infinity of succession, a geometrical infinity: each individual is an unit, many individuals compose a finite number, and the whole species is the infinite multitude. Thus in the same manner as a geometrical infinity may be demonstrated not to exist, so we may be assured that an infinite progression or expansion does not exist; that it is only an abstract idea, a retrenchment of the idea of finity, of which we take away the limits that necessarily terminate all size; and that, of course, we must reject from philosophy every opinion which leads to an idea of the actual existence of geometrical or arithmetical infinity.

The partizans, therefore, of this opinion must acknowledge, that their infinity of succession and multiplication is, in fact, only an indeterminate or indefinite number; a number greater than any we can have an idea of, but which is not infinite. This being granted, they will tell us, that the first seed of an elm, for example, which does not weigh a grain, really contains all the organic particles necessary for the formation of this, and every other tree of the same kind which ever shall appear. But what do they explain to us by this answer? Is it not cutting the knot instead of untying it, and eluding the question when it should be resolved.

When we ask how beings are multiplied? and it is answered that this multiplication was compleatly made in the first body, is it not acknowledging that they are ignorant how it is made, and renouncing the will of conceiving it? The question is asked, how one body produces its like? and it is answered, that the whole was created at once. Can we receive this as a solution? for whether one or a million of generations have passed the like difficulty remains, and so far from explaining the supposition of an indefinite number of germs, increases the obscurity, and renders it incomprehensible.

I own, that in this circumstance, it is easier to start objections than to establish probabilities, and that the question of reproduction is of such subtle nature, as possibly never to be fully resolved; but then we should search whether it is totally inscrutable, and by that examination, we shall discover all that is possible to be known of the subject; or at least, why we must remain ignorant of it.

There are two kinds of questions, some belonging to the first causes, the others have only particular effects; for example, if it is asked, why matter is impenetrable? it must either remain unanswered, or be replied to by saying, matter is impenetrable, because it is impenetrable. It will be the same with respect to all the general qualities of matter, whether relative to gravity, extension, motion or rest; no other reply can be given, and we shall not be surprised that such is the case, if we attentively consider, that in order to give a reason for a thing, we must have a different subject from which we may deduce a comparison, and therefore if the reason of a general cause is asked, that is, of a quality which belongs to all in general, and of which we have no subject to which it does not belong, we are consequently unable to reason upon it; from thence it is demonstrable, it would be useless to make such enquiries, since we should go against the supposition that quality is general and universal.

If, on the contrary, the reason of a particular effect depends immediately on one of the general causes above mentioned, and whether it partakes of the general effect immediately, or by a chain of other effects, the question will be equally solved, provided we distinctly perceive the dependence these effects have on each other, and the connections there are between them.

But if the particular effect, of which we enquire the reason, does not appear to depend on these general effects, nor to have any analogy with other known effects, then this effect, being the only one of its kind, and having nothing in common with other effects, at least known to us, the question is insolvable: because, not having, in this point, any known subject which has any connection with that we would explain, there is nothing from whence we can draw the reason sought after. When the reason of a general cause is demanded, it is unanswerable, because it exists in every object; and, on the other hand, the reason of a singular or isolated effect is not found, because not any thing known has the same qualities. We cannot explain the reason of a general effect, without discovering one more general; whereas the reason of an isolated effect may be explained by the discovery of some other relative effect, which although we are ignorant of at present, chance or experience may bring to light.

Besides these, there is another kind of question, which may be called, the question of fact. For example. Why do trees, dogs, &c. exist? All these fact questions are totally insoluble, for those who answer them by final causes do not consider that they take the effect for the cause; the connection particular objects have with us having no influence on their origin. Moral affinity can never become a physical reason.

We must carefully distinguish these questions where the why is used, from those where the how is employed, and more so from those where the how many is mentioned. Why is always relative to the cause of the effect, or to the effect itself. How is relative to the mode from which the effect springs, and the how many has relation only to the proportionate quantity of the effect.

All these distinctions being explained, let us proceed to examine the question concerning the reproduction of bodies. If it is asked, why animals and vegetables reproduce? we shall clearly discover, that this being a question of fact, it is insolvable, and useless to endeavour at the solution of it. But if it is asked, how animals and vegetables reproduce; we reply by relating the history of the generation of every species of animal, and of the reproduction of each distinct vegetable; but, after having run over all the methods of an animal engendering its resemblance, accompanied even with the most exact observations, we shall find it has only taught us facts without indicating causes; and that the apparent methods which Nature makes use of for reproduction, do not appear to have any connection with the effects resulting therefrom; we shall be still obliged to ask, what is the secret mode by which she enables different bodies to propagate their own species?

This question is very different from the first and second; it gives liberty of enquiry and admits the employment of imagination, and therefore is not insolvable, for it does not immediately belong to a general cause; nor is it entirely a question of fact, for provided we can conceive a mode of reproduction dependent upon, or not repugnant to, original causes, we shall have gained a satisfactory answer; and the more it shall have a connection with other effects of nature, the better foundation will it be raised upon.

By the question itself it is, therefore, permitted to form hypotheses, and to select that which shall appear to have the greatest analogy with the other phenomena of nature. But we must exclude from the number all those which supposes the thing already done; for example, such as suppose that all the germs of the same species were contained in the first seed, or that every reproduction is a new creation, and immediate effect of the Almighty's will; because these hypotheses are questions of fact, and on which it is impossible to reason. We must also reject every hypothesis which might have final causes for its object; such as, we might say, that reproduction is made in order for the living to supply the place of the dead, that the earth may be always covered with vegetables, and peopled with animals; that man may find plenty for his subsistence, &c. because these hypotheses, instead of explaining the effects by physical causes, are founded only on arbitrary connections and moral agreements. At the same time we must not rely on these absolute axioms and physical problems, which so many people have improperly made use of, as principles; for example, there is no fecundation made apart from the body, nulla fœcondatio extra corpus; every living thing is produced from an egg; all generation supposes sexes, &c. We must not take these maxims in an absolute sense, but consider them only as signifying things generally performed in one particular mode rather than in any other.

Let us, therefore, search after an hypothesis which has not any of those defects, and by which we cannot fall into any of these inconveniences; if, then, we do not succeed in the explanation of the mechanical power Nature makes use of to effect the reproduction of beings, we shall, at least, arrive at something more probable than what has hitherto been advanced.

As we can make moulds, by which we can give to the external parts of bodies whatever figure we please, let us suppose Nature can form the same, by which she not only bestows on bodies the external figure but also the internal. Would not this be one mode by which reproduction may be performed?

Let us, then, consider on what foundation this supposition is raised: let us examine if it contains any thing contradictory, and afterwards we shall discover what consequences may be derived from it. Though our senses are only judges of the external parts of bodies, we perfectly comprehend external affection and different figures. We can also imitate Nature, by representing external figures by different modes, as by painting, sculpture, and moulds; but although our senses are only judges of external qualities, we know there are internal qualities, some of which are general, as gravity. This quality, or power, does not act relatively to surfaces, but proportionably to the masses, or quantities of matter; there is, therefore, very active qualities in Nature, which even penetrate bodies to the most internal parts; but we shall never gain a perfect idea of these qualities, because, not being external, they cannot fall within the compass of our senses; but we can compare their effects, and deduce analogies therefrom, to answer for the effect of similar qualities.

If our eyes, instead of representing to us the surface of objects only, were so formed as to shew us the internal parts alone, we should then have clear ideas of the latter, without the smallest knowledge of the former. In this supposition the internal moulds, which I have supposed to be made use of by Nature, might be as easily seen and conceived as the moulds for external figures. In that case we should have modes of imitating the internal parts of bodies as we now have for the external. These internal moulds, although we cannot acquire, Nature may be possessed of, as she is of the qualities of gravity, which penetrate to the internal particles of matter. The supposition of these moulds being formed on good analogies it only remains for us to examine if it includes any contradiction.

It may be argued that the expression of an internal mould includes two contradictory ideas; that the idea of a mould can only be related to the surface, and that the internal, according to this, must have a connection with the whole mass, and, therefore, it might as well be called a massive surface as an internal mould.

I admit, that when we are about to represent ideas which have not hitherto been expressed, we are obliged to make use of terms which seem contradictory; for this reason philosophers have often employed foreign terms on such occasions, instead of applying those in common use, and which have a received signification; but this artifice is useless, since we can shew the opposition is only in the words, and that there is nothing contradictory in the idea. Now I affirm that a simple idea cannot contain a contradiction, that is, when we can form an idea of a thing; if this idea is simple it cannot be compounded; it cannot include any other idea, and, consequently, it will contain nothing opposite nor contrary.

Simple ideas are not only the primary apprehensions which strike us by the senses, but also the primary comparisons which form from those apprehensions; for the first apprehension, itself is always a comparison. The idea of the size of an object, or of its remoteness, necessarily includes a comparison with bulk or distance in general; therefore, when an idea only includes comparison it must be regarded as simple, and from that circumstance, as containing nothing contradictory. Such is the idea of the internal mould. There is a quality in Nature, called gravity, which penetrates the internal parts of bodies. I take the idea of internal mould relatively to this quality, and, therefore, including only comparison, it bears not any contradiction.

Let us now see the consequences that may be deduced from this supposition; let us also search after facts corresponding therewith, as it will become so much the more probable, as the number of analogies shall be greater. Let us begin by unfolding this idea of internal moulds, and by explaining in what manner we understand it, we shall be brought to conceive the modes of reproduction.

Nature, in general, seems to have a greater tendency to life than death, and to organize bodies as much as possible; the multiplication of germs, which may be infinitely encreased, is a proof of it; and we may assert with safety, that if all matter is not organized, it is because organized beings destroy each other; or we can augment as much as we please the quantity of living and vegetating beings, but we cannot augment the quantity of stones or other inanimate matters. This seems to indicate that the most common work of Nature is the production of the organic part, and in which her power knows no bounds.

To render this intelligible, let us make a calculation of what a single germ might produce. The seed of an elm, which does not weigh the hundredth part of an ounce, at the end of 100 years will produce a tree whose volume will be 60 cubic feet. At the tenth year this tree will have produced 1000 seeds, which being all sown, at the end of 100 years would each have also a volume equal to 60 cubic feet. Thus in 110 years there is produced more than 60,000 cubic feet of organized matter; 10 years more there will be 10,000,000 of fathoms, without including the 10,000 encreased every year, which would make 100,000 more; and ten years after there will be three times that number; thus in 130 years a single shoot will produce a volume of organized matter, which would fill up a space of 1000 cubic leagues; 10 years after it would comprehend a 1,000,000, and in 10 years more 1,000,000 times 1,000,000 cubic leagues; so that in 150 years the whole terrestrial globe might be entirely converted into one single kind of organized matter. In this production of organized body Nature would know no bounds, if it were not for the resistance of matters which are not susceptible of organization, and this proves that she does not incline to form inanimate but organized beings, and that in this she never stops but when irresistible inconveniences are opposed thereto. What we have already said on the seed of an elm may be said of any other; and it would be easy to demonstrate, that if we were to hatch every egg produced by hens for the space of 30 years, there would be a sufficient number of fowls to cover the whole surface of the earth.

These kind of calculations demonstrate that organic formation is the most common work of Nature, and, apparently, that which costs her the least labour. But I will go farther; the general division which we ought to make of matter seems to me to be in living and dead matter, instead of organized and brute; the brute is only that matter produced by the death of animals or vegetables; I could prove it by that enormous quantity of shells, and other cast-off matters of living animals, which compose the principal part of stones, marble, chalk, marle, earth, turf, and other substances, which we call brute matter, and which are only the ruins of dead animals or vegetables; but a reflection, which seems to me well founded, will, perhaps, make it better understood.

Having meditated on the activity of Nature to produce organized bodies, and seen that her power, in this respect, is not limited; having proved that infinity of organic living particles, which constitute life, must exist; having shewn that the living body costs the least trouble to Nature, I now search after the principal causes of death and destruction, and I find that bodies in general, which have the power of converting matter into their proper substance, and to assimilate the parts of other bodies, are the greatest destroyers. Fire, for example, turns into its own substance almost every species of matter, and is the greatest means of destruction known to us. Animals seem to participate of the qualities of flame; their internal heat is a kind of fire; therefore, after fire, animals are the greatest destroyers, and they assimilate and convert into their own substance every matter which may serve them for food: but although these two causes of destruction are very considerable, and their effects perpetually incline to the annihilation of organized beings, the cause of reproduction is infinitely more powerful and active; she seems to borrow, even from destruction itself, means to multiply, since assimilation, which is one cause of death, is at the same time a necessary means of producing life.

To destroy an organized being is, as we have observed, only to separate the organic particles of which it is composed; these particles remain separated till they are re-united by some active power. But what is this active power?—It is the power which animals and vegetables have to assimilate the matter that serves them for food; and is not this the same, or at least has it not great connection with that which is the cause of reproduction?

CHAPTER III.

OF NUTRITION AND GROWTH.

The body of an animal is a kind of internal mould, in which the nutritive matter assimilates itself with the whole in such a manner that, without changing the order and proportion of the parts, each receives an augmentation, and it is this augmentation of bulk which some have called expansion, because they imagined every difficulty would be removed by the supposition that the animal was completely formed in the embryo, and that it would be easy to conceive that its parts would expand, or unfold in proportion as it would increase by the addition of accessory matter.

But if we would have a clear idea of this augmentation and expansion, how can it be done otherwise than by considering the animal body, and each of its parts, as so many internal moulds which receive the accessory matter in the order that results from the position of all their parts? This expansion cannot be made by the addition to the surfaces alone, but, on the contrary, by an intimate susception which penetrates the mass, and thus increases the size of the parts, without changing the form, from whence it is necessary that the matter which serves for this expansion should penetrate the internal part in all its dimensions; it is also as necessary that this penetration be made in a certain order and proportion, so that no one point can receive more than another, without which some parts would expand quicker than others, and the form be entirely changed. Now what can prescribe this rule to accessory matter, and constrain it to arrive perpetually and proportionally to every point of the internal parts, except we conceive an internal mould?

It therefore appears certain that the body of an animal or vegetable is an internal mould of a constant form, but where their masses may augment proportionably, by the extension of this mould in all its external and internal dimensions. That this extension also is made by the intus-susception of any accessory or foreign matter which penetrates the internal part, and becomes similar to the form and identical substance with the matter of the moulds themselves.

But of what nature is this matter which the animal or vegetable assimilates with its own substance? what can be the nature of that power which gives it the activity and necessary motion to penetrate the internal mould? and if such a power does exist, must it not be similar to that by which the internal mould itself would be produced?

These three questions include all that can be desired on this subject, and seem to depend on each other so much, that I am persuaded the reproduction of an animal or vegetable cannot be explained in a satisfactory manner, if a clear idea of the mode of the operation of nutrition is not obtained; we must, therefore, examine these three questions separately, in order to compare the consequences resulting therefrom.

The first, which relates to the nutritive nature of this matter, is in part resolved by the reasons we have already given, and will be fully demonstrated in the succeeding chapter. We will shew that there exists an infinity of living organic particles in Nature; that their production is of little expence to Nature, since their existence is constant and invariable, and that the causes of death only separate without destroying them. Therefore the matter which the animal or vegetable assimilates is an organic matter of the same nature as the animal or vegetable itself, and which consequently can augment the size without changing the form or quality of the matter of the mould, since it is in fact of the same form and quality as that which it is constituted with. Thus, in the quantity of aliments which the animal takes to support life, and to keep its organs in play, and in the sap, which the vegetable takes up by its roots and leaves, there is a great part thrown off by transpiration, secretion, and other excretory modes, and only a small portion retained for the nourishment of the parts and their expansion. It is very probable, that in the body of an animal or vegetable there is formed a separation of the brute particles of the aliments and the organic; that the first are carried off by the causes just mentioned; that only organic particles remain, and that the distribution of them is made by means of some active power which conducts them to every part in an exact proportion, insomuch that neither receive more or less than is needful for its equal nutrition, growth, or expansion.

The second question, What can be the active power which causes this organic matter to penetrate and incorporate itself with this internal mould? By the preceding chapter it appears, that there exists in Nature powers relative to the internal part of matter, and which have no relation with its external qualities. These powers, as already observed, will never come under our cognizance, because their action is made on the internal part of the body, whereas our senses cannot reach beyond what is external; it is therefore evident, that we shall never have a clear idea of the penetrating powers, nor of the manner by which they act; but it is not less certain that they exist, than that by their means most effects of Nature are produced; we must attribute to them the effects of nutrition and expansion, which cannot be effected by any other means than the penetration of the most intimate recesses of the original mould: in the same mode as gravity penetrates all parts of matter, so the power which impels or attracts the organic particles of food, penetrates into the internal parts of organized bodies, and as those bodies have a certain form, which we call the internal mould, the organic particles, impelled by the action of the penetrating force, cannot enter therein but in a certain order relative to this form, which consequently it cannot change, but only augment its dimensions, and thus produce the growth of organized bodies; and if in the organized body, expanded by this means, there are some particles whose external and internal forms are like that of the whole body, from those reproduction will proceed.

The third question, Is it not by a similar power the internal mould itself is reproduced? It appears, that it is not only a similar but the same power which causes expansion and reproduction, for in an organized body which expands, if there is some particle like the whole, it is sufficient for that particle to become one day an organized body itself, perfectly similar to that of which it made a part. This particle will not at first present a figure striking enough for us to compare with the whole body; but when separated from that body, and receiving proper nourishment, it will begin to expand, and in a short time present a similar being, both externally and internally, as the body from which it had been separated: thus a willow or polypus, which contain more organic particles similar to the whole than most other substances, if cut into ever such a number of pieces, from each piece will spring a body similar to that from whence it was divided.

Now in a body, every particle of which is like itself, the organization is the most simple, as we have observed in the first chapter; for it is only the repetition of the same form, and a composition of similar figures, all organized alike. It is for this reason that the most simple bodies, or the most imperfect kinds, are reproduced with the greatest ease, and in the greatest plenty; whereas, if an organized body contains only some few particles like itself, then, as such alone can arrive to the second expansion, consequently the reproduction will be more difficult, and not so abundant in number; the organization of these bodies will also be more compounded, because the more the organized parts differ from the whole, the more the organization of this body will be perfect, and the more difficult the production will be.

Nourishment, expansion, and propagation, then, are the effects of one and the same cause. The organized body is nourished by the particles of aliments analogous to it; it expands by the intimate susception of organical parts which agree with it, and it propagates because it contains some original particles which resemble itself. It only remains to examine, whether these similar organic particles come into the organized body by nutriment, or whether they were there before, and have an independent existence. If we suppose the latter, we shall fall in with the doctrine of the infinity of parts, or similar germs contained one in the other; the insufficiency and absurdity of which hypothesis we have already shewn; we must therefore conclude that similar parts are extracted from the food; and after what has been said, we hope to explain the manner in which the organic molecules are formed, and how the minute particles unite.

There is, as we have said, a separation of the parts in the nutriment; the organic from those analogous to the animal or vegetable, by transpiration and other excretory modes; the organical remain and serve for the expansion and nutriment of the body. But these organic parts must be of various kinds, and as each part of the body receives only those similar to itself, and that in due proportion, it is very natural to imagine, that the superfluity of this organic matter will be sent back from every part of the body into one or more places, where all these organical molecules uniting, form small organized bodies like the first, and to which nothing is wanting but the mode of expansion for them to become individuals of the same species; for every part of the body sending back organized parts, like those of which they themselves are composed, it is necessary, that from the union of all these parts, there should result organized bodies like the first. This being admitted, may we not conclude this is the reason why, during the time of expansion and growth, organized bodies cannot produce, because the parts which expand absorb the whole of the organic molecules which belong to them, and not having any superfluous parts, consequently are incapable of reproduction.

This explanation of nutrition and reproduction will not probably be received by those who admit but of a certain number of mechanical principles, and reject all which do not depend on them; and as what has been said of nutrition and expansion comes under the latter description, they will possibly treat it as unworthy dependance. But I am quite of a different opinion from these philosophers; for it appears to me that, by admitting only a certain number of mechanical principles, they do not see how greatly they contract the bounds of philosophy, and that for one phenomenon that can be explained by a system so confined, a thousand would be found exceeding its limits.

The idea of explaining every phenomenon in nature by mechanical principles was certainly a great and beautiful exertion, and which Descartes first attempted. But this idea is only a project, and if properly founded, have we the means of performing it? These mechanical principles are the extent of matter, its impenetrability, its motion, its external figure, its divisibility, and the communication of movement by impulsion, by elasticity, &c. The particular ideas of each of these qualities we have acquired by our senses, and regard them as principles, because they are general and belong to all matter. But are we certain these qualities are the only ones which matter possesses, or rather, must we not think these qualities, which we take for principles, are only modes of perception; and that if our senses were differently formed, we should discover in matter, qualities different from those which we have enumerated? To admit only those qualities to matter which are known to us, seems to be a vain and unfounded pretension. Matter may have many general qualities which we shall ever be ignorant of; she may also have others that human assiduity may discover, in the same manner as has recently been done with respect to gravity, which alike exists in all matter. The cause of impulsion, and such other mechanical principles, will always be as impossible to find out as that of attraction, or such other general quality. From hence is it not very reasonable to say, that mechanical principles are nothing but general effects, which experience has pointed out to us in matter, and that every time a new general effect is discovered, either by reflection, comparison, measure, or experience, a new mechanical principle will be gained, which may be used with as much certainty and advantage as any we are now acquainted with?

The defect of Aristotle's philosophy was making use of particular effects as common causes; and that of Descartes in making use of only a few general effects as causes, and excluding all the rest. The philosophy which appears to me would be the least deficient, is that where general effects are only made use of for causes, and seeking to augment the number of them, by endeavouring to generalize particular effects.

In my explanation of expansion and reproduction, I admit the received mechanical principles, the penetrating force of weight, and, by analogy, I have strove to point out that there are other penetrating powers existing in organized bodies, which experience has confirmed. I have proved by facts, that matter inclines to organization, and that there exists an infinite number of organic particles. I have therefore only generalized some observations, without having advanced any thing contrary to mechanical principles, when that term is used as it ought to be understood, as denoting the general effects of Nature.

CHAPTER IV.

OF THE GENERATION OF ANIMALS.

As human and animal organization is the most perfect and compounded, their propagation is also the most difficult and least abundant; I here except those animals which, like the fresh-water polypus or worms, are reproduced from their divided parts, as trees are by slips, or plants by their divided roots or suckers; also those which may be found to multiply without copulation; it appears to me that the nature of those have been sufficiently explained in the preceding chapter; and from which, in every kind where an individual produces its resemblance, it is easy to deduce the explanation of the reproduction from expansion and nutrition.

But how shall we apply this mode of reasoning to the generation of man and animals distinguished by sexes, and where the concurrence of two individuals is required? We understand, by what has just been advanced, how each individual can produce its like; but we do not conceive how a male and a female produces a third.

Before I answer this question, I cannot avoid observing, that all those who have written upon this subject have confined their systems to the generation of man and animals, without paying any attention to other kinds of generation which Nature presents us with, and reproduction in general; and as the generation of man and animals is the most complicated of all kinds, their researches have been attended with great disadvantages, not only by attacking the most difficult point, but also by having no subject of comparison, from which they could draw a solution of the question. To this it is that I principally attribute the little success of their labours; but by the road I have taken we may arrive at the explanation of the phenomena of every kind of generation in a satisfactory manner.

The generation of man will serve us for an example. I take him in his infancy, and I conceive that the expansion and growth of the different parts of his body being made by the intimate penetration of organic molecules analogous to each of its parts, all these organic molecules are absorbed in his earliest years, and serve only for the expansion and augmentation of his various members, consequently there is little or no superfluity until the expansion is entirely completed; and this is the reason why children are incapable of propagation; but when the body has attained the greatest part of its growth, it begins to have no longer need of so great a quantity of organic particles, and the superfluity, therefore, is sent back from each part of the body into the destined reservoirs for its reception. These reservoirs are the testicles and seminal vessels, and it is at this period that the expansion of the body is nearly completed, when the commencement of puberty is dated, and every circumstance indicates the superabundance of nutriment; the voice alters and takes a deeper tone; the beard begins to appear, and other parts of the body are covered with hair; those parts which are appointed for generation take a quick growth; the seminal liquor fills the prepared reservoirs, and when the plentitude is too great, even without any provocation, and during the time of sleep, it emits from the body. In the female this superabundance is more strongly marked, it discovers itself by periodical evacuation, which begin and end with the faculty of propagating, by the quick growth of the breasts, and by an attraction in the sexual parts, as shall be explained.

I think, therefore, that the organical molecules, sent from every part of the body into the testicles and seminal vessels of the male, and into the ovarium of the female, forms there the seminal liquor, which is, as has been observed, in both sexes, a kind of extract of every part of the body. These organical molecules, instead of uniting and forming an individual, like the one in which they are contained, can only unite when the seminal liquors of the two sexes are mixed; and when there is more organical molecules of the male than of the female, in such mixture the produce will be a male; and, on the contrary, when there is more of the female then a female will be the result.

I do not mean to say that the organic molecules of either could unite to form small organized bodies of themselves, but that it is necessary a mixture of the seminal fluid of both sexes should take place, and that it is only those formed in that mixture which can expand and become individuals. These small moving bodies, called spermatic animals, are seen, by a microscope, in the seminal liquor of every male, and are, probably, small organized bodies, proceeding from the individual which contains them, but which cannot expand or produce any thing of themselves. We shall evince that there are the same in the seminal liquor of the female, and shall indicate the place where this liquor is to be found.

It is very possible that organical molecules are, at first, only a kind of fœtus of a small organized body, in which there are only essential parts. We shall not enter into a detail of proofs, in this respect, but content ourselves with remarking, that the pretended spermatic animals, which we have been speaking of, might possibly be but imperfectly organized, or that these pretended animals are only living organic particles, common both to animals and vegetables, or, at most, only the first union of those particles.

But let us return to our principal object. How can we conceive, it may be asked, that the superfluous particles can be sent back from every part of the body, and afterwards unite when the seminal liquor of the two sexes are mixed? Besides, is it certain that this mixture is made? Has it not been pretended that the female did not furnish any fluid of this kind? Is it certain that the liquor of the male enters the matrix, &c.

To the first question I answer, if what I have said on the subject of the penetration of the internal mould by organic molecules, in nutrition or expansion, be well understood, it will easily be conceived that these molecules, not being able any longer to penetrate those parts they did before, they will be necessitated to take a different road, and consequently arrive at some part, as the testicles or seminal vessels; for to explain the animal economy, and the different movements of the human body, solely by mechanical principles, is the same as if a man would give an account of a picture by shutting his eyes and feeling on it; for it is evident that neither the circulation of the blood, nor the motion of the muscles, nor the animal functions, can be explained by impulsion, nor other common laws of mechanics: it is as evident that nutrition, expansion, and reproduction, is made by other laws, why therefore not admit of acting and penetrating powers on the masses of bodies, since we have examples of it in gravity, in magnetical attractions, and in chemical affinities? And as we are now convinced by facts, and the multitude of constant and uniform observations, that there exists in nature powers which do not act by the mode of impulsion, why should we not make use of those powers as mechanical principles? Why should we exclude them from the explanations of effects, which we are convinced they produce? Why should we be confined to employ only the power of impulsion? Is not this like judging of a picture by the touch, and explaining the phenomena of the mass by those of the surface, and the penetrating power by superficial action? Is not this making use of one sense instead of another; and, on the whole, is it not confining the faculty of reasoning on a small number of mechanical principles, totally inadequate to follow the various productions of nature.

But those penetrating powers being once admitted, is it not natural to suppose that the most analogous particles will unite and bind themselves intimately together; that each part of the body will appropriate the most agreeable to itself, and that from the superfluity of all these particles there will be formed a seminal fluid, which will contain all the organic molecules necessary to form a small organized body, perfectly like that from which this fluid is extracted? A power like that which was necessary to make them penetrate into each part, and produce expansion, may be sufficient to collect them in an organized form, like that of the body in which they originated.

I conceive, that in the aliments we take there is a great quantity of organical molecules, which needs no serious proof, since we live on animals and vegetables, which are organized substances. In the stomach and intestines a separation is made of the gross parts, which are thrown off by the excretories. The chyle, which is the purest part of the aliment, enters into the lacteal vessels, and from thence is transported into every part of the body. By the motion of the circulation it purifies itself from all inorganical molecules, which are thrown off by secretion and transpiration; but the organic particles remain, because they are analogous to the blood, and that from thence there is a power of affinity which retains them afterwards; for as the whole mass of blood passes many times through the body, I apprehend, that in this continual circulation every particular part of the body attracts the particles most analogous to it, without interrupting the course of the others. In this manner every part is expanded and nourished, not, as it is commonly said, by a simple addition of the parts, and a superficial increase, but by an intimate penetration of substance, produced by a power which acts on every point of the mass; and when the parts of the body are at a certain growth, and almost filled with these analogous particles, as their substance is become more solid, I conceive they then lose the faculty of attracting or receiving those particles, but as the circulation will continue to carry them to every part of the body, which not being any longer able to admit them as before, must necessarily be deposited in some particular part, as in the testicles or seminal vessels. This fluid extract of the male, when mixed with that of the female, the similar particles, possessing a penetrating force, unite and form a small organized body like one of the two sexes, and no more than expansion is wanting to render it a similar individual, and which it afterwards receives in the womb of the female.

The second question, Whether the female has really a seminal liquor similar to the male? demands some discussion. I shall first observe, as a certain matter, that if such a fluid exists, the manner in which the emission of the female is made is not so apparent as by the male, being in general retained within the body.[BJ] The ancients so little doubted of the female having a seminal liquor, that it was by the different mode of its emission that they distinguished the male from the female. But physicians, who have endeavoured to explain generation by the egg, or by spermatic animalcules, insinuate that females have no particular fluid, that we have been deceived by taking the mucus for the seminal, and that the supposition of the ancients upon this subject was destitute of all foundation. Nevertheless this fluid does exist, and it has only been doubted by those who chose to give way to systems, and from the difficulty of discovering the parts which serve for its reservoirs. The fluid which issues from the glands at the neck of the womb, and at the orifice of the urethra, has no apparent reservoir, and as it flows outwardly it cannot be thought to be the prolific liquor, since it cannot concur in the formation of the fœtus which is performed within the matrix. The prolific fluid of the female must have a reservoir in another part. It flows even in great plenty, although such a quantity is not necessary, no more than in the male, for the production of the embryo. It is sufficient for propagation if ever so little of the male fluid enters the matrix, so it meets with the smallest drop of that of the female; therefore the observations of some anatomists, who have pretended that the seminal liquor of the male does not enter the womb, makes nothing against what we have advanced, especially as other anatomists, who rely on observations, have pretended the contrary. But the subject will be better discussed in the subsequent pages.