Miscellanea Curiosa. (continued 4)
Reading edition
I have transcrib'd the intire Paragraph, because it contains his whole Hypothesis of the Diastole, and all the notice that he takes of it through his whole Work. But how slender soever this may prove, it is the most substantial that I have any where met with, except a late one of Mr. Cowper, which is properly an Improvement of this, and shall be consider'd in the Sequel.
But if Contraction be the sole Action of these Fibres (as this Great Man confesses it to be) and as indeed it is of all Muscular Fibres, I wonder how so judicious a Writer came to slip into such an Absurdity, as to call their Distention (vulgarly but improperly call'd Relaxation) a Motion of Restitution. For from the Nature of those Fibres, and their disposition in the Structure of the Heart, the natural State of the Heart appears manifestly to be Tonical, and its Dilatation a State of Violence; and consequently, the Constriction is the true motion of Restitution, and the State to which it will spontaneously return, when the Force is taken off, which is the work of the Intercostal Muscles and Diaphragm.
Thus we are left still to seek for the true Cause of the Diastole, which seems to me to be the main and most difficult Phænomenon, relating to the Heart and the Circulation of the Blood. But in Mr. Cowper's ingenious Introduction to his Anatomy of Humane Bodies, I find the Share which Dr. Lower hints the Blood to have in that Action, further prosecuted, and improved into the main Instrument of the Dilatation of the Heart, wherein I agree intirely with him. But as to the manner, and reasons of its being so very instrumental, I can't be so perfectly of his mind.
The Heart (says this accurate Anatomist) of an Animal bears a great Analogy to the Pendulums of those Artificial Automata, Clocks and Watches, whilst its motion is performed like that of other Muscles, the Blood doing the Office of a Pondus.
This Explication, being but a Simile without a distinct application to Particulars, is beside so very short, that I can at best but give a conjecture at the meaning; which if I mistake, I shall deserve to be excused, and expect to be better inform'd.
By the Bloods doing the Office of a Pondus, I suppose he means, that the Blood contributes in the same manner to the motion of the Heart, as the Weights do to that of the Pendulum of a Clock. If so, the Blood, according to him, must be the Instrument of Constriction; and Dilatation must be the Natural State, or Spontaneous Motion, to which it wou'd, when under no violence, return; the contrary of which, I presume, will appear e're I have done.
But if he means, that the Blood in its reflux, by gravitating on the Auricles and Ventricles, dilates and expands 'em, acting therein as a Counterpoise to its contractions as a Muscle, I cou'd wish his Design had not bound him up to so narrow a compass, and that he had given us an explication at large of so abstruse and so important a Phænomenon: Because the Specifick Gravity of the Blood seems to me a cause by no means alone adequate to the effect, which it is here suppos'd to produce.
For, if the Blood acts only as a weight by meer gravitation, then that part of it only which descends from the Parts above the Heart can be employ'd in that Action. This at the largest computation can't amount to Five pound weight, and must, according to the computation of Borellus, force a Machine, that is able to overcome a resistance of 135,000l. I leave every Man to deduct what he shall upon examination find reasonably to be deducted, and yet shall rest secure, that it is not to be effected in the least with so small a Weight.
But neither does the Refluent Blood gravitate in any such proportion, as I have here assign'd. For to make a true estimate of its Gravitation, we must consider the Circumstances of the Liquor suppos'd to gravitate; in which it very much resembles Water inclos'd in a recurve Tube, of which, if the length of the two Legs be equal, it may be suspended in the Air full of Water, with the Extremities downwards, without losing a drop, although the Diameter of those Legs should be very unequal. The Case of the Arteries and Veins is pretty near a parallel to a Tube, so fill'd and inverted. For, if the Arteries and Veins be continued Tubes, (as by the Microscope they are made to appear) then supposing their contents to have no other determination of motion, than their own weight wou'd give them, the contain'd Fluids must be Counterpoises to each other. For the Veins and Arteries being join'd at the smaller Extremities, and the larger of both terminating in the same parallel Line, it is impossible, according to the Laws of Hydrostaticks, that the contents of either shou'd overbalance t'other. How far then must it fall short of forcing the natural Power and Resistance of so strong a Muscle as the Heart, by meer Gravitation?
The Blood indeed has a Progressive Motion through its Vessels, wherein it differs from Water, in a recurve Tube, in the Experiment above-stated. But, if the natural Gravitation of the Blood contributes nothing to the Dilatation of the Heart, this progressive Motion will not be found much more sufficient. For, as this Motion is deriv'd intirely from the Heart's Constriction (as all Accounts hitherto derive it) cou'd the Blood be suppos'd to re-act upon it by the Heart, with all the force first impress'd upon it by the Heart, it would be insufficient, unless we will suppose the Force communicated to be superiour to the Power Communicant, which is absurd.
But when the just and necessary Deductions for the Impediments, which the Blood meets with in its Progress through the Vessels, shall be made, the remaining Force will be found so exceeding weak, that to prop the Blood through the Veins may be a task alone too great for so small a Power, without charging it with the additional difficulty of forcing the Muscle of the Heart.
Alphonsus Borellus, after a great deal of solemn pains taken to shew his Care and Exactness, and to possess his Reader of the Truth of his Calculations, casts up the force of the Heart, and the Muscular Coat of the Arteries, to be together equal to a weight of 3,750l. and allots them a Resistance equal to 180,000l. to overcome which is 45 to 1. To make up for a disproportion, by his own confession, incredible to those who have not consider'd the Matter as he had done, he flings into the Scale the additional Force of Percussion, which he leaves indefinite, and thinks sufficient to force any quiescent finite Resistance whatsoever.
But as this Account and Hypothesis are part of a Posthumous Work (if a liberty of Conjecture may be allow'd in so uncertain a Matter,) I shou'd suspect, that these Papers were left unfinish'd by Borellus; or at least, that in many places the last Hand was never put to them. For neither in this Place, nor any other of this Work, does he account for any more than the Systole of the Heart, and the resistance which is made to the progressive motion of the Blood in the Arteries only. This alone he found to exceed the Power of the Heart so prodigiously, that he seems to shuffle it off his Hands with a general and precarious Solution, as a difficulty that he was desirous to be rid of. For, having ascrib'd this stupendous (as he himself calls it) effect to the Energy of Percussion, he takes no care to satisfie his Reader any farther about it, or to refer him, or give him the expectation of Satisfaction any where else; although he has an express Treatise on the Force of Percussion, which was written preparatory to this, and to which he frequently refers in other Places of this Work. But what confirms my suspicion, that this part was intended for a farther Revise by the Author, is, that he has left the Progress of the Blood through the Veins, and the Diastole of the Heart, absolutely untouch'd, tho' they are Difficulties of a much greater magnitude than this, which he has attempted to account so slightly for: For, in these he is excluded the benefit of Percussion, and has yet a greater resistance to overcome without it. Omissions of this kind are so unusual with this Author, where-ever he knows himself to go upon sure grounds, that it is to me an Argument, that he doubted the sufficience of his Percussion, and reserv'd these important Phænomena for farther Consideration, without plunging himself into such an Absurdity, as to ascribe to Percussion any such Energy as to be able (so broken as it returns to the Heart) by its re-action to force that Power, from whence only it was at first deriv'd.
Dr. Lower, and Mr. Cowper, deliver their Opinions of the Cause of the Dilatation of the Heart so very short, and without any Arguments to support them, that by exposing them naked, they seem rather to discourse of it transiently, as Men oblig'd by the Nature of their Subjects to say something of it, than solicitous to give any full or satisfactory Account; and therefore I shall proceed no farther upon them here.
But though the Hypothesis of Borellus may, in this Case, be found precarious or insufficient (a Misfortune that has befallen him in divers other Particulars) his Theory holds still good. At least it ought to be allow'd, in justice to his great Abilities and Exactness, till some Body convicts him of some material Error in his Calculations, which has not as yet been done by any Body, that I know of.
Supposing then the force of the Heart, and of the Muscular Coat of the Arteries, as likewise of the resistance, which they must overcome, to be computed with any degree of accuracy, there remains yet such a prodigious disproportion to be accounted for, as requires some more powerful Agent, than any yet assign'd, to make up the deficiency.
What assistance the Heart receives from the action of the Thorax towards the facilitating its Contraction, without which assistance there cou'd have been no Systole, has been already shewn. But neither the Intercostal Muscles, or Diaphragm, which are so instrumental in that part of its action, can contribute any thing to the Diastole; because they serve only to enlarge the Cavity of the Thorax, and thereby to open a passage to the Blood from the Heart, and promote its Constriction.
Whatever therefore the force is, that dilates the Heart, and is the cause of the Diastole, it must be equal to that of the Heart, the Intercostal Muscles and Diaphragm; to all which it acts as an Antagonist. I take no notice of the Serratus Major Anticus, and other Muscles; which have an obscure share in the Elevation of the Costæ, because as much may reasonably be deducted upon the account of the Obliquus externus Abdominis, and other Muscles; which having their Insertions on some of the lower Ribs are as instrumental towards the Depression of them, and so balance the Account. But the chief use of these is in violent Respiration: In ordinary Respiration their share is small.
Such a real Power (which may in the least be suspected of any share in this Action) is hard, perhaps impossible to be found in the Machine of any Animal Body; and yet without some such Antagonist, it is as impossible the Circulation of the Blood should be maintain'd. All the Engines yet discover'd within the Body, conspire towards the Constriction of the Heart, which is the State of Quiescence, to which it naturally tends. Yet we find it alternately in a State of Violence, that is, of Dilatation; and this upon necessity, because upon this Alternation depends all Animal Life.
Some sufficient Cause External must therefore be found, to produce this great Phænomenon; which Cause must be either in the Air, or Atmosphere, because we have no constant and immediate Commerce with any other Mediums.
Some great Physicians observing this, and that depriv'd by whatsoever means of Communication with the external Air, we became instantly extinct, have imagin'd, that in the Act of Inspiration certain purer parts of the Air, mixed with the Blood in the Lungs, and was convey'd with it to the Heart, where it nourish'd a sort of Vital Flame, which was the Cause of this reciprocal Æstus of the Heart. Others not quite so gross, rejecting an Actual Flame, have fancied, that these fine Parts of Air mixing with the Blood in the Ventricles of the Heart, produc'd an Effervescence which dilated it. But these Fancies have been long since exploded and condemn'd upon ample Conviction; and 'tis a Point yet undetermin'd, whether any Air does mix with the Blood at all in the Lungs, or not.
But supposing, that some Air may insinuate it self into the Pulmonary Vein, it can no other way dilate the Heart than by an Effervescence in the Left Ventricle, which wou'd not dilate the Right. But this Opinion is contradicted by Autopsie, and too laboriously confuted by others, to be brought upon the Stage again here.
There remains therefore only the gross Body of the Atmosphere to be considered, which is undoubtedly the true Antagonist to all those Muscles, which serve for ordinary Inspiration, and the Constriction of the Heart. This will appear more evidently, if we consider not only the Power, but the Necessity of its Action upon Animal Bodies, as well as the want of other sufficient Agents.
The Heart is a Solitary Muscle of very great strength, and the Intercostal Muscles and Diaphragm, which likewise have no Antagonists, are a vast additional Force, which must be balanc'd by the contrary Action of some equivalent Power or other. For, tho' the Action of the Intercostal Muscles be voluntary, that does not exempt them from the condition of all other Muscles serving for voluntary motion, which wou'd be in a State of perpetual Contraction, notwithstanding any Influence of the Will, were it not for the Libration of Antagonist Muscles. This Libration between other Muscles, is answer'd by the Weight of the incumbent Atmosphere, which presses upon the Thorax and other parts of the Body. And, as in all other voluntary Motions the influence of the Will only gives a prevalence to one of its two Powers before equilibrated, so here it serves to enable those Muscles to lift up a weight too ponderous for their strength not so assisted; and therefore as soon as that assistance is withdrawn, the Costæ are again depress'd by the meer Gravitation of the Atmosphere, which wou'd otherwise remain elevated through the natural Tendency of those Muscles to Contraction.
This is evidently prov'd from the Torricellian Experiments, and those made upon Animals in Mr. Boyle's Engine; where, as soon as the Air is withdrawn, and the pressure thereby taken off, the Intercostal Muscles and Diaphragm are contracted, and the Ribs elevated in an instant, and can't by any Power of the Will be made to subside, till the Air is again let in to bear them forcibly down.
It were scarce worth while to take notice here of a Mistake of the Learned Dr. Willis, were it not for the great Authority of the Man, which is almost sufficient to keep Error in countenance. |De Respirationis Organis & Usu. | The Doctor having observ'd, that the Fibres of the External and Internal Intercostal Muscles ran in a contrary order, as it were, decussating each other, takes occasion from thence to fansie, that there was an opposition in their Office; and that as the External serv'd to raise up the Ribs, the Internal drew them down again, forgetting at that time, That, when a contractile Body is fasten'd at the several ends to Points unequally moveable, let the Contraction happen in what part or manner soever, the more moveable Point must be drawn towards the less moveable: By which Rule, whether External or Internal Intercostals be contracted, the lower Ribs will be forc'd to approach the upper, that is, be rais'd up.
As in the Elevation of the Costæ, the Blood, by the passage that is open'd for it, is in a manner solicited into the Lungs; so in the Depression of them, by the subsidence of the Lungs, and the Contraction of the Blood-Vessels, both which are consequent thereof, the Blood is forcibly driven, as it were with an Embolum, through the Pulmonary Vein into the Left Ventricle of the Heart. And this, together with the general Compression of the Body by the weight of the Atmosphere, which surrounds and presses upon the whole Surface of it, is that Power which causes the Blood to mount in the Veins, after the force impress'd upon it by the Heart is broken and spent, and which is sufficient to force the Heart from its natural State to Dilatation.
He that is able to compute the weight of a Column of Air, equal to the Surface of the whole Body, will readily grant it a power sufficient for the Effects, which are here ascrib'd to it. And when he considers, that the Bodies of Animals are compressible Machines, he will find that it must of necessity affect them in the manner here laid down. But though our Bodies be entirely compos'd of Tubuli, or Vessels fill'd with Fluids; yet this pressure, how great soever, being equal, cou'd have no effect upon them, if the superficial Dimensions were not easily variable; because being compress'd on all parts with the same degree of Force, the contain'd Fluids cou'd not any where begin to recede, and make way for the rest to follow, but wou'd remain as fix'd and immoveable as if they were actually solid. But by the Dilatation of the Thorax, room is made for the Fluids to move, and by the Coarctation of it, fresh motion is imprest, which is the main Spring whereby the Circulation is set and kept going.
This reciprocal Dilatation and Contraction of the superficial Dimensions of the Body, seems so necessary to Animal Life, that there is not any Animal so imperfect as to want it, at least none to the inward Structure, of which our Anatomical Discoveries have yet reach'd. For, tho' most kinds of Fish and Insects, want both moveable Ribs and Lungs, and consequently have no dilatable Thorax, yet that want is made up to 'em by an Analogous Mechanism, answering sufficiently the Necessities of their Life.
Those Fishes which have no Lungs, have Gills, which do the Office of Lungs, receiving and expelling alternately the Water, whereby the Blood-Vessels suffer the same alteration of Dimensions, that they do in the Lungs of more perfect Animals.
The Lungs or Air-Vessels of Insects, are yet exceedingly more different in Structure, Distribution, and Situation from those of perfect Animals, than those of Fishes are, and yet in their Use and Action agree perfectly with both; that is, receiving and expelling the Air, and varying the Dimensions and Capacities of the Blood-Vessels. These having no Thorax, or separate Cavity for the Heart and Air-Vessels, have the latter distributed through the whole Trunk of their Bodies, by which they communicate with the External Air through several Spiracula or Vent-holes, to which are fasten'd so many little Tracheæ, or Wind-pipes, which thence send their Branches to all the Muscles and Viscera, and seem to accompany the Blood-Vessels all over the Body, as they do in the Lungs only of perfect Animals. By this disposition in every Inspiration, the whole Body of these little Animals is inflated, and in every Expiration compress'd; and consequently the Blood-Vessels must suffer a Vicissitude of Extension and Contraction, and a greater motion must thereby be impress'd upon the Fluids contain'd in them, than the Heart, which does not in those Creatures appear to be Muscular, seems capable of giving.
The only Animal that is exempted from this necessary condition of Breathing, or receiving and expelling alternately some Fluid into and out of the Body, is a Fœtus. But this, while included in the Womb, has little more than a vegetative Life, and ought scarce to be reckon'd among the number of Animals. For, were it not for that small share of Muscular Motion, which it exercises in the Womb, it might without absurdity be accounted for as a Graft upon, or Branch of the Mother.
Concerning the immediate Matter, and Means of Life, and Nutrition, Authors are not agreed, nor is it the business of this place to reconcile, or decide their Differences, but to account for the Motion of the Blood through the Vessels only. In order to this, it will be necessary to observe, that the Pulsation of the Heart in a Fœtus is so very weak and obscure, and the Motion of the Blood so extream slow and languid, as to be scarce, if at all perceivable, as has been experienced in the Dissection of Puppies before Respiration had. To |Boyle of the Elasticity of Air. Pechlinus de Aeris & Alimenti defectu.| produce such a feeble Palpitation, and creeping Motion, no greater force seems to be required, than may be deriv'd from the Communication between the Vessels of the Mother and Fœtus in the Placenta. I am not ignorant, that divers very Learned Anatomists (whom the Crowd have implicitly follow'd) have absolutely rejected all Communication between these Vessels. But, with submission to Great Authorities, I think they have acted arbitrarily, and without sufficient Warrant from Reason or Experiment: For neither are the Arguments which they bring against it conclusive, nor the Office which they assign to the Umbilical Vessels in lieu of it, proper, or natural to those Vessels, or the reality of the Fact made out by any substantial Reasons. Those that reject this Communication usually do it in favour of one or both of these Opinions, that the Arteries of the Uterus do deposite a Nutritive Juice, or a Juice impregnate with Air in the Placenta, which is suck'd in by the Umbilical Vein, and convey'd to the Fœtus, for the necessary Uses of Nutrition and Life. Now those that patronize either of these Opinions, lead Nature an unnecessary Dance. For if the Maternal Blood does really contain any such Nutritious, or any such necessary Aerial Particles, why shou'd they be separated and extravasated, to be with difficulty receiv'd into the Umbilical Vein, and again mixt with the Blood, when they might more easily have been imparted by the plain simple way of Transfusion from the Arteries of the Mother to the Veins of the Fœtus. And, that this is the course which Nature takes in this Case, I am perswaded from the easiness and simplicity of the Method, which readily performs what might be perhaps in vain expected from the other, and wou'd over and above find them, what they seem to grope so blindly about for, a first Mover of the Blood in a Fœtus.
Those that contend for the conveyance of the Nutricious Juice, through the Umbilical Vein from the Placenta, are forc'd upon two Difficulties next to Absurdities. For first they are oblig'd to make this Vein, which, as all other Veins, seems dedicated to the Re-conveyance of Blood only, the proper and immediate Chanel, thro' which a very different Liquour is to be carried; and next, to give a Power of Attraction or Suction to it; because the Nutricious Juice, which it is thus destin'd to carry, is both viscous and stagnant, and has neither force to drive, nor subtilty to penetrate, or insinuate it self into the Capillary Veins; and therefore must be drawn or suck'd as Milk is from the Breast, to which the Placenta and its Nutricious Juice are by the Favourers of them expresly compar'd. But if this were the sole use of the Placenta, and Umbilical Vessels, why were the Umbilical Arteries sent along with the Vein? Their business is not to bring any thing back to the Fœtus, nor can they contribute any thing to the benefit of the Mother; for the Uterine Arteries bring all to the Placenta, the Umbilical Vein carries it to the Fœtus, and the Uterine Veins convey back again the Surcharge of the Mother's Blood; the Umbilical Arteries only, have nothing to do, and are superfluous and impertinent, which is contrary to the constant Practice of Nature. Yet if Autopsie did in the least countenance this Hypothesis, some Defence might still be made; but we find in the Umbilical Vein of a Fœtus nothing but Florid Blood, such as in all probability it received immediately from the Arteries of the Mother without any mixture. And therefore I can't help concluding, that this Opinion engages its Favourers in some Absurdity, without Necessity and without Proof.
They that from the Placenta supply the Body of the Fœtus with Air, are as much distress'd as t'other; for they are forc'd to beg the Question twice, which, even when granted, will not answer their Ends. First, they suppose, that an intimate mixture or confusion of Air with the Blood, is necessary for the support of Animal Life, a Postulatum, which perhaps the former part of this Discourse may have render'd unnecessary; and next, that the Fœtus is supply'd with Air from, and its Blood mix'd with it in the Placenta.
But here again they fetch a Compass without necessity or proof. For if a mixture of Air were necessary to a Fœtus, why should it be separated from the Mother's Blood, and not rather both communicated together, since it is so much more easie and commodious? But neither does the Placenta seem to be instructed and provided for the separation of Air, but of a much grosser Fluid, destin'd to some other use, which Autopsie confirms: Yet, were both these Opinions true, they are however defective, and the Circular Motion of the Blood unprovided for.
By the way of Transfusion, this great Phænomenon is naturally accounted for, and the Ends, for which the other two Hypotheses were devis'd, might both be answer'd with more ease. For the Hysterick Arteries transmitting their Blood immediately to the Umbilical Vein, may very easily transmit such Nutricious Juices or Aerìal Particles, as are contain'd in the Blood, along with it, without depositing them by the way. By this means so much of the Impulse of the Mother's Blood is preserv'd, as suffices to maintain that languid Circulation which a Fœtus enjoys. For the Blood being driven through the Arteries of the Uterus into the Umbilical Vein, is convey'd directly to the Sinus of the Porta, and thence by a short and direct Passage through the Cava to the Heart; where passing through the Foramen Ovale to the Left Ventricle, and through the Canalis Arteriosus from the Right and Pulmonary Artery, it is all deliver'd without coming at the Lungs to the Aorta, and from thence again by the Umbilical Arteries to the Veins of the Uterus, making a sort of Epicycle to the main Circulation in the Mother.
As this Opinion is Favour'd by the Structure and Disposition of the Blood-Vessels on both Parts, so there is nothing in it difficult to be conceiv'd, or repugnant to Experience. Late Discoveries have made it appear, that the Arteries and Veins are continu'd Tubes, and that the latter contain nothing but what they receive from the former, and no Reason appears why we shou'd think this Method to be varied in the Placenta. On the other hand, if the Arteries of the Uterus were continued to the Veins of the same part, and those of the Fœtus in like manner, without communicating with each other, their Confluence in the Placenta seems to be altogether impertinent, and of no use, and the Umbilical Arteries and Vein fram'd for no other Service or Purpose, than to give the Blood room for an idle Sally.
Thus the Reasonableness of this old Opinion may be vindicated, but the Certainty of it rests upon stronger Proof. Mr. Cowper, to whose happy Industry we owe the Confirmation of many ancient Discoveries, and the Benefit of some new ones, has the Honour to re-establish this old, but long exploded Truth. For by pouring Mercury into a Branch of the Uterine Arterie of a Cow, that went into one of the Cotyledones of the Uterus, he fill'd those Branches of the Umbilical Veins, which went from that Cotyledon to the Navel of the Fœtus; which, with a part of the Uterus, he keeps prepared by him.
It would be a weak Objection, to alledge, That the Observation and Experiment being made on the Uterus of a Cow, the Inference would not hold from thence to a Woman, the one being Glanduliferous, and the other Placentiferous; since every one of these Cotyledones, or Uterine Glandules, is in all respects a little Placenta, and all the difference between them is in number, name, and magnitude. Why Ruminants differ in this Particular from other Viviparous Animals, is beside the Subject of our present Enquiry. But the great Flux of Blood, which constantly follows upon drawing the Placenta from Women (which is frequently so great as to cost them their Lives) is as plain a demonstration to Reason of the Continuity of the Vessels, as Mr. Cowper's Experiments is to the Eye.
I have heard it objected by very Learned Men, that if there were such a Continuity of Vessels, and such Transfusion of Blood, the Fœtus must necessarily perish through loss of Blood, upon the separation of the Placenta from the Uterus; but that, on the contrary, no visible Flux of Blood does follow while the Fœtus continues wrapt in the Membrane, in which Condition it may be kept alive some Hours. To this it may be answer'd, that the Circulation in the Fœtus, being deriv'd from the Mother, may be suppos'd wholly to cease upon the cutting off the Communication between them, till it is again renew'd more forcibly by Respiration. But if we allow the motion already impress'd upon the Blood to be sufficient to keep it going a little while; yet it must needs be so exceeding languid, that the meer resistance of the External Air must be more than enough to hinder any Efflux of Blood from a Fœtus before Respiration. How long Life may be preserv'd without an actual Circulation of the Blood, is a Question not of this place. But we have been convinc'd by many and notorious Observations and Experiments, that Life has been recover'd a long time after all tokens of Respiration, Circulation, or even Life it self, have disappear'd; so that we can't think the first Solution either impossible or improbable.
I expect to be told, that in the early Days of Gestation in Viviparous Animals, there is no Placenta, or any Adhesion of the Umbilical Vessels to any part of the Mother, and consequently no such Transfusion; and that in Oviparous there is no continuity, or communication of Vessels of any kind, during the whole time of Incubation.
But these Objections carry neither the Weight nor Difficulty along with them, that they may be suppos'd to do; for in those Days there is neither Blood or Blood-Vessels, and consequently there can be no Circulation of the Blood; and the Embryo, of what Species soever, is no more than a Vegetable at that time; nor does the Fœtus of any Viviparous Creature enjoy any Circulation, or shew any signs of Animal Life, till after those Vessels, as well as others requisite to the Circulation, are compleated.
It must be confess'd, that Oviparous Animals are denied the benefit of this Communication; but that want is sufficiently compensated by a peculiar Mechanism, which directly answers the ends of Respiration, and the pressure of the Atmosphere upon the Fœtus. There is at the obtuse end of an Egg a small Cavity fill'd with Air, which is the succedaneous Instrument to the Respiratory Organs. For as soon as the Contents begin to be warm'd by the Incubation of the Hen, or any analogous Heat of Furnace or Dunghill, the several Humours of the Egg require a fermentative motion, and the Air contain'd in the Cavity or Vesicle, at the obtuse end of the Egg, is rarefied, and the Vesicle extended and enlarg'd, and consequently the other Contents are comprest; to which the fermentative motion naturally resists. But both Bodies being as well compressible as dilatable, and both having an expansive motion imprest upon them by Incubation, the Compression and Renitency will be mutual, but varied in degree, according as either, through the variation of Circumstances, shall prevail. By this means, an Alternation of Compression and Dilatation will be produc'd in both, answering the respiratory motion, by which a motion will be communicated, which, as soon as the Organs by which it should be regulated are compleated, will in the Body of the Pullus be regular and circulatory.
Fabricius ab Aquapendente, and after him, our Great Dr. Harvey, have assign'd divers Uses to this Cavity or Air Vesicle, the Extravagance of which have perhaps deterr'd others from enquiring so much into the Use, as the Importance of it requir'd. But though I can't agree to that Perspiration, Refrigeration, and Respiration, which they make it the Instrument of; yet perhaps the Air, that was inclos'd in that Cavity, may through the Augmentation of the Body of the Pullus, and its own Rarefaction (which is at last so great as to occupy half the Shell) break the Membrane, which separated it from the Pullus, and thereby give so much Respiration as to form the chirping Voice, which is often heard before the breaking of the Shell, and with it give an addition of Strength to enable it to break the Shell. But how it should respire sooner, is to me inconceivable.
There are many Problems of great seeming Difficulty, the Solutions of which flow naturally from what has been laid down here: But intending to prosecute this Subject farther, and to treat of the Impediments of Respiration, and the Consequences of Respiration obstructed or intermitted, I shall reserve them for that Opportunity, and content my self here to attempt the Harveyan Problem only, which has given abundance of Authors so much perplexity.
That incomparable Philosopher enquires, Why a Fœtus, taken out of the Uterus with the Membranes intire, shall live in Water some Hours without communication with the External Air; whereas if it be taken out and suffer'd once to breath, it can't afterwards survive a Moment without the benefit of Respiration.
Granting the Fact to be as he has deliver'd it, which yet is not so in all Cases, the main Difficulty is grounded on a Mistake, which from the stating of the Question I find this Great Man to have slipt into. For he thinks, that a Fœtus is sooner suffocated after having once breath'd, than if it had not breath'd at all, and that by breathing it had contracted something which render'd it more perishable. Idem tamen secundis exutus, (says he) si semel aerem intra Pulmones attraxerit, postea ne momentum quidem temporis absque eo durare possit, sed confestim moriatur. And presently after, Siquidem constat, fœtum, postquam eum semel hauserit, citius suffocari; quam cum ab illo prorsus accebatur. The Doctor observing a Fœtus to live longer without Respiration, and to dispence better with the want of Air while included in the Membranes intire, than it cou'd afterwards; infers thence, that the Air does in the first Act of Inspiration impress upon the Lungs some quality, which renders it ever after more indispensably necessary. But allowing his Observation, I must yet deny his Inference to be good: For deprive a Fœtus of means of respiring, and then take it out of the Membranes, and it shall be as soon suffocated, as if it had respired before. This proves, that this necessity of intercourse with the Air, by way of the Lungs, is not the Offspring, but the Parent of Respiration, and that, that Learned Man was drawn into a Fallacy of Non causa pro causa.
The Reason of this Necessity is the pressure of the External Air upon the Surface of the Body, from which it was defended by the Interposition of the Membranes, and the Humours contain'd, which are not so compressible as the Body of the Fœtus it self. So soon therefore as the Fœtus is excluded, and expos'd to the immediate contact of the ambient Atmosphere, the Vessels and all the Cavities of the Body must necessarily be so compress'd, that the Fluids can't have room for motion, and consequently the Fœtus could have no Life, if Nature had not contriv'd by the motion of the Thorax to remove and admit that pressure alternately, and thereby to impress a motion on the Fluids, which is the Spring of Life. But this motion of the Thorax being any way suppress'd, the equal pressure of the Atmosphere on all parts, occasions a total Cessation of motion, which is Death.
I shall prosecute this Subject no farther now, nor trouble the Reader with any Apology, for dissenting from those Great Men herein named; because, I hope, I have done it with Modesty, and all the Respect due to so great Authorities, and have assign'd nothing which is not Matter of Fact uncontroverted, or deduc'd from it by plain Mechanical Necessity.
Some Thoughts and Experiments concerning Vegetation. By John Woodward, M. D. of the College of Physicians, and R. S. and Professor of Physick in Gresham College.
THE Ancients generally intitled the Earth to the Production of the Animals, Vegetables, and other Bodies upon and about it; and that for that Reason 'twas, that they gave it so frequently the Epithets of Parent and Mother[1]. They were of opinion, that it furnished forth the Matter whereof those Bodies consist; and receiv'd it all back again at their Dissolution for the Composure of others. Even those who asserted four Elements, supposed that the Earth was the Matter that constituted those Bodies; and that Water and the rest, serv'd only for the Conveyance and Distribution of that Matter, in order to the forming and composition of them. 'Tis true, Thales, a Philosopher of the first Rank in those early Ages, has been thought to have Sentiments very different from these; but that without just Grounds, as I think I have sufficiently prov'd in another Paper, which I am ready to produce.
But though Antiquity thus gave its Vote for Terrestrial Matter, several of the Moderns, and some of very great Name too, both here and abroad, have gone quite counter, and given theirs in behalf of Water. The Dignity of the Persons that have espoused it, as well as their Numbers, renders this Doctrine very considerable, and well worth our enquiring into. The great Restorer of Philosophy in this last Age, my Lord Bacon, is of Opinion, That for Nourishment of Vegetables, the Water is almost all in all; and that the Earth doth but keep the Plant upright, and save it from over-heat, and over-cold[2]. Others there are who are still more express; and assert Water to be the only Principle or Ingredient of all Natural Things. They suppose that, I cannot tell by what Process of Nature, Water is transmuted into Stones, into Plants, and in brief, all other Substances whatever. Helmont,[3] particularly, and his Followers, are very positive in this; and offer some Experiments to render it credible. Nay, a very Extraordinary Person of our own Nation[4] tries those Experiments over again; and discovers a great Propensity to the same Thoughts and Opinion they had; declaring for this Transmutation of Water into Plants and other Bodies, though with great Modesty and Deference, which was his usual manner.
The Experiments they insist upon are chiefly two; the first is, that Mint, and several other Plants prosper and thrive very greatly in Water. The other is this; they take a certain quantity of Earth, and bake it in an Oven; then they weigh it, and put it into an Earthen Pot. Having well water'd this Earth, they make choice of some fit Plant, which, being first carefully weigh'd, they set in it. There they let it grow, continuing to water it for some time, till 'tis much advanced in bigness: Then they take it up; and though the Bulk and Weight of the Plant be much greater than when first set, yet upon baking the Earth, and weighing it, as at first, they find it little or not at all diminished in weight; and therefore conclude, 'tis not the Earth but Water, that nourishes and is turn'd into the Substance of the Plant.
I must confess I cannot see how this Experiment can ever be made with the nicety and justness that is requisite, in order to build upon it so much as these Gentlemen do. 'Tis hard to weigh Earth in that quantity, or Plants of the size of those they mention, with any great exactness; or to bake the Earth with that accuracy, as to reduce it twice to just the same Driness. But I may wave all this; for though the Experiment be never so easily practicable, and all the Accidents of it exactly as they set forth, yet nothing like what they infer can possibly be concluded from it; unless Water, which they so plentifully bestow upon the Plant in this Experiment, be pure, homogeneous, and not charged with any terrestrial Mixture; for if it be, the Plant after all may owe its Growth and Encrease intirely to that.
Some Waters are indeed so very clear and transparent, that one would not easily suspect any terrestrial Matter were latent in them; but they may be highly saturated with such Matter, though the Eye be not presently able to descry or discern it. 'Tis true, Earth is an Opake Body; but it may be so far dissolved, reduced to so extreme small Particles, and these so diffused through the watry Mass, as not sensibly to impede Vision, or render the Water much the less diaphanous. Silver is an Opake, and indeed a very dense Body; and yet, if perfectly dissolved in Spirit of Nitre, or Aqua Fortis, that is rectified and thorowly fine, it does not darken the Menstruum, or render it less pellucid than before[5]. And other Instances there are, that oftentimes great quantities of Opake Matter are sustain'd in Fluids, without considerably striking the Eye, or being perceiv'd by it. So that were there Water any where found so pure, that the quickest Eye could discover in it no terrestrial Intermixture; that would be far short of a Proof, that in reality there was none.
But after all, even the clearest Water is very far from being pure and wholly defecate, in any part of the World that I can learn. For ours here, I have had an Opportunity of examining it over a good part of England; and cannot say I ever met with any, that, however fresh and newly taken out of the Spring, did not exhibit, even to the naked Eye, great numbers of exceeding small terrestrial Particles disseminated through all parts of it. Thicker and crasser Water exhibits them in still greater Plenty.
These are of two general kinds. The one a vegetable terrestrial Matter, consisting of very different Corpuscles; some whereof are proper for the formation and increment of one sort of Plant, and some of another; as also some for the Nourishment of one part of the same Plant, and some of another. The other kind of Particles sustain'd in Water are of a Mineral Nature. These likewise are of different sorts. In some Springs we find common Salt, in others Vitriol, in others Alum, Nitre, Sparr, Ochre, &c. nay, frequently several of these, or other Minerals, all in the same Spring; the Water as it drains and passes thorough the Strata of Stone, Earth, and the like, taking up and bearing along such loose Mineral Corpuscles, as it meets with in the Pores and Interstices of those Strata, and bringing them on with it quite to the Spring. All Water whatever is much charg'd with the Vegetable Matter, this being fine, light, and easily moveable. For the Mineral, the Water of Springs contains more of it than that of Rivers, especially when at distance from their Sources; and that of Rivers more than the Water that falls in Rain. This I have learn'd from several Trials, which I must not give Account of here; my Drift in this place being only to evince the Existence of Terrestrial Matter in Water.
Any one who desires farther Satisfaction in this, may easily obtain it, if he only put Water into a clear Glass Viol, stopping it close, to keep Dust and other exterior Matter out, and letting it stand, without stirring it for some Days: He will then find a considerable Quantity of terrestrial Matter in the Water, however pure and free it might appear when first put into the Viol. He will in a very short time observe, as I have frequently done, the Corpuscles that were at first, while the Water was agitated and kept in motion, separate, and hardly visible[6], by degrees, as the Water permits, by its becoming more still and at rest, assembling and combining together; by that means forming somewhat larger and more conspicuous Moleculæ. Afterwards he may behold these joining and fixing each to other, by that means forming large thin Masses, appearing like Nubeculæ, or Clouds in the Water; which grow more thick and opake, by the continual appulse and accretion of fresh Matter. If the said Matter be chiefly of the Vegetable kind, it will be sustain'd in the Water; and discover at length a green Colour, becoming still more and more of that Colour, I mean an higher and more saturate Green, as the Matter thickens and encreases. That this Matter inclines so much to that Colour, is the less strange, since we see so large a share of it, when constituting Vegetables wearing the same Colour in them. But if there be any considerable quantity of meer Mineral Matter in the Water, this, being of a greater specifick Gravity than the Vegetable, as the Particles of it unite and combine in such Number, till they form a Molecula, the Impetus of whose Gravity surpasses that of the Resistance of the Water, subsides a great deal of it to the bottom. Nor does it only fall down it self, but frequently entangling with the Vegetable Nubeculæ, forces them down along with it.
The Reason why Bodies, when dissolved and reduced to extreme small Parts, are sustain'd in Liquors that are of less specifick Gravity than those Bodies are, hath been pointed at by a late ingenious Member of this Society[7]. He is indeed far from having adjusted all the Momenta of this Affair; however it must be admitted, that, in the dividing or solution of Bodies, their Surfaces do not decrease in the same Proportion that their Bulk does. Now the Gravity of a Body, which is the Cause of its sinking or tendency downwards, is commensurate to its Bulk; but the resistance that the Liquor makes, is proportion'd, not to the Bulk, but to the Extent of the Surface of the Body immersed in it. Whence 'tis plain, a Body may be so far divided, that its Parts may be sustain'd in a Fluid, whose specifick Gravity is less than that of the said Body. Nay, 'tis Matter of Fact, that they frequently are so; and we daily see Menstrua supporting the Parts of Metals, and other Bodies, that are of six, ten, nay, almost twenty times the specifick Gravity of those Menstrua. And as the Parts of Bodies when divided, are thus supported in a Fluid; so when they occur and unite again, they must sink of course, and fall to the Bottom.
Upon the whole, 'tis palpable and beyond reasonable Contest, that Water contains in it a very considerable Quantity of terrestrial Matter. Now the Question is, to which of these, the Water, or the Earthly Matter sustain'd in it, Vegetables owe their Growth and Augment: For deciding of which, I conceive the following Experiments may afford some Light; and I can safely say, they were made with due Care and Exactness.
Anno 1691.
I chose several Glass Vials, that were all, as near as possible, of the same shape and bigness. After I had put what Water I thought fit into every one of them, and taken an Account of the weight of it, I strain'd and ty'd over the Orifice of each Vial, a Piece of Parchment, having an hole in the middle of it, large enough to admit the Stem of the Plant I design'd to set in the Vial, without confining or streightning it, so as to impede its Growth. My Intention in this, was to prevent the inclosed Water from evaporating, or ascending any other way than only through the Plant to be set therein. Then I made choice of several Sprigs of Mint, and other Plants, that were, as near as I could possibly judge, alike fresh, sound, and lively. Having taken the weight of each, I placed it in a Vial, order'd as above; and as the Plant imbib'd and drew off the Water, I took care to add more of the same from time to time, keeping an Account of the weight of all I added. Each of the Glasses were, for better distinction, and the more easie keeping a Register of all Circumstances, noted with a different Mark or Letter, A, B, C, &c. and all set in a Row in the same Window, in such manner that all might partake alike of Air, Light, and Sun. Thus they continued from July the Twentieth, to October the Fifth, which was just Seventy Seven Days. Then I took them out, weigh'd the Water in each Vial, and the Plant likewise, adding to its weight that of all the Leaves that had fallen off during the time it stood thus. And Lastly, I computed how much each Plant had gain'd; and how much Water was spent upon it. The Particulars are as follow.
(A.) Common Spear-Mint, set in Spring-Water. The Planted weighed when put in, July 20. just 27 Grains; when taken forth, October 5. 42 Grains: So that in this space of 77 Days, it had gained in weight 15 Grains.
The whole Quantity of Water expended, during these 77 Days, amounted to 2558 Grains. Consequently the weight of the Water taken up, was 1708⁄15 times as much as the Plant had got in weight.
(B.) Common Spear-Mint, Rain-Water. The Mint weigh'd, when put in, Gr. 28¼; when taken out Gr. 45¾, having gain'd in 77 Days Gr. 17½.
The Dispendium of the Water Gr. 3004, which was 17122⁄35 times as much as the Plant had received in weight.
(C.) Common Spear-Mint, Thames-water. The Plant when put in, Gr. 28, when taken forth, Gr. 54. So that in 77 Days it had gained Gr. 26.
The Water expended, amounted to Gr. 2493. which was 9523⁄26 times as much as the additional weight of the Mint.
(D.) Common Solanum, or Night-shade: Spring-water. The Plant weigh'd, when put in, Gr. 49; when taken out, 106; having gain'd in 77 Days 57 Gr.
The Water expended during the said time, was 3708 Gr. which was 653⁄57 times as much as the Augment of the Plant.
This Specimen had several Buds upon it, when first set in the Water. These in some Days became fair Flowers, which were at length succeeded by Berries.
(E.) Lathyris seu Cataputia Gerh. Spring-Water. It weigh'd, when put in, Gr. 98. when taken forth, Gr. 101½. The additional weight for the whole 77 Days, being but Gr. 3½.
The Quantity of Water spent upon it during that time, Gr. 2501. which is 7144⁄7 times as much as the Plant was augmented.
Several other Plants were try'd, that did not thrive in Water, or succeed any better than the Cataputia foregoing: But 'tis besides my purpose to give a particular Account of them here.
(F, G.) These Two Vials were fill'd, the former (F) with Rain, the other with Spring-water, at the same time as those above-mention'd were; and stood as long as they did. But they had neither of them any Plant; my Design in these being only to inform my self, whether any Water exhaled out of the Glasses, otherwise than thorow the Bodies of the Plants. The Orifices of these two Glasses were cover'd with Parchment; each piece of it being perforated with an hole of the same bigness with those of the Vials above. In this I suspended a bit of Stick, about the thickness of the Stem of one of the aforesaid Plants, but not reaching down to the Surface of the included Water. I put them in thus, that the Water in these might not have more Scope to evaporate than that in the other Vials. Thus they stood the whole 77 Days in the same Window with the rest; when, upon Examination, I found none of the Water in these wasted or gone off. Tho' I observed both in these, and the rest, especially after hot Weather, small Drops of Water, not unlike Dew, adhering to the Insides of the Glasses, that Part of them, I mean, that was above the Surface of the enclosed Water.
The Water in these two Glasses that had no Plants in them, at the end of the Experiment, exhibited a larger Quantity of Terrestrial Matter than that in any of those that had the Plants in them did. The Sediment at the bottom of the Vials was greater; and the Nubeculæ, diffus'd through the Body of the Water, thicker. And of that which was in the others, some of it proceeded from certain small Leaves that had fallen from that part of the Stems of the Plants that was within the Water, wherein they rotted and dissolved. The Terrestrial Matter in the Rain-water was finer than that in the Spring-water.
Anno 1692.
The Glasses made use of in this, were of the same sort with those in the former Experiment; and cover'd over with Parchment in like manner. The Plants here were all Spear-Mint; the most kindly, fresh, sprightly Shoots I could chuse. The Water, and the Plants were weigh'd as above; and the Vials set in a Line, in a South Window: where they stood from June the 2d to July 28. which was just 56 Days.
(H.) Hyde-Park Conduit Water, alone. The Mint weighed, when put in, 127 Gr. when taken out, 255 Gr. The whole Quantity of Water expended upon this Plant, amounted to 14190 Gr.
This was all along a very kindly Plant; and had run up to above two Foot in height. It had shot but one considerable collateral Branch; but had sent forth many and long Roots, from which sprung very numerous, though small and short, lesser Fibres. These lesser Roots came out of the larger on two opposite sides, for the most part; so that each Root, with its Fibrillæ, appear'd not unlike a small Feather. To these Fibrillæ adher'd pretty must Terrestrial Matter. In the Water, which was at last thick and turbid, was a green Substance, resembling a fine thin Conserva.
(I.) The same Water, alone. The Mint weigh'd, when put in, 110 Gr. when taken out, 249. Water expended, 13140 Gr.
This Plant was as kindly as the former, but had shot no collateral Branches. Its Roots, the Water, and the green Substance, all much as in the former.
(K.) Hyde-Park Conduit-water, in which was dissolved an Ounce and half of Common Garden-earth. The Mint weigh'd, when put in, 76 Gr. when taken out, 244 Gr. Water expended, Gr. 10731.
This Plant, though it had the Misfortune to be annoy'd with many small Insects that hapn'd to fix upon it; yet had shot very considerable collateral Branches; and at least as many Roots as either that in H or I; which had a much greater Quantity of Terrestrial Matter adhering to the Extremities of them. The same green Substance here, that was in the two preceding.
(L.) Hyde-Park Water, with the same Quantity of Garden-mould as in the former. The Mint weigh'd, when put in, 92 Gr. when taken out, 376 Gr. The Water expended 14950 Gr.
This Plant was far more flourishing than any of the precedent; had several very considerable collateral Branches, and very numerous Roots, to which Terrestrial Matter adhered very copiously.
The Earth in both these Glasses was very sensibly and considerably wasted, and less than when first put in. The same sort of green Substance here as in those above.
(M.) Hyde-Park Water, distilled off with a gentle Still. The Mint weigh'd, when put in, 114 Gr. when taken out 155. The Water expended, 8803 Gr.
This Plant was pretty kindly; had two small collateral Branches, and several Roots, though not so many as that in H or I, but as much Terrestrial Matter adhering to them as those had. The Water was pretty thick; having very numerous small Terrestrial Particles swimming in it, and some Sediment at the bottom of the Glass. This Glass had none of the green Matter above mentioned, in it.
(N.) The Residue of the Water, which remain'd in the Still after that in M, was distill'd off. It was very turbid, and as high-colour'd (reddish) as ordinary Beer. The Mint weigh'd, when put in, 81 Gr. when taken out, 175 Gr. Water expended, 4344 Gr. This Plant was very lively; and had sent out six collateral Branches, and several Roots.
(O.) Hyde-Park Conduit-water, in which was dissolved a Drachm of Nitre. The Mint set in this suddenly began to wither and decay; and died in a few Days: As likewise did two more Sprigs, that were set in it, successively. In another Glass I dissolv'd an Ounce of good Garden-mould, and a Drachm of Nitre, and in a third, half an Ounce of Wood ashes, and a Drachm of Nitre; but the Plants in these succeeded no better than in the former. In other Glasses I dissolved several other sorts of Earths, Clays, Marles, and variety of Manures, &c. I set Mint in distill'd Mint-water; and other Experiments I made, of several kinds, in order to get Light and Information, what hastened or retarded, promoted or impeded Vegetation; but these do not belong to the Head I am now upon.
(P.) Hyde-Park Conduit-water. In this I fix'd a Glass-Tube about ten Inches long, the Bore about one sixth of an Inch in Diameter, fill'd with very fine and white Sand, which I kept from falling down out of the Tube into the Vial, by tying a thin piece of Silk over that end of the Tube that was downwards. Upon Immersion of the lower end of it into the Water, this by little and little ascended quite to the upper Orifice of the Tube. And yet, in all the fifty six Days which it stood thus, a very inconsiderable Quantity of Water had gone off, viz. scarce twenty Grains; though the Sand continued moist up to the top till the very last. The Water had imparted a green Tincture to the Sand, quite to the very top of the Tube. And, in the Vial, it had precipitated a greenish Sediment, mix'd with black. To the bottom and sides of the Tube, as far as 'twas immers'd in the Water, adher'd pretty much of the green Substance describ'd above. Other like Tubes I fill'd with Cotton, Lint, Pith of Elder, and several other porous Vegetable Substances; setting some of them in clear Water; others in Water tinged with Saffron, Cochinele, &c. And several other Trials were made, in order to give a mechanical Representation of the motion and distribution of the Juices in Plants; and of some other Phænomena observable in Vegetation, which I shall not give the Particulars of here, as being not of use to my present design.
(Q, R, S, &c.) Several Plants set in Vials, ordered in like manner as those above, in October, and the following colder Months. These throve not near so much; nor did the Water ascend in nigh the quantity it did in the better Seasons, in which the before recited Trials were made.
Some Reflections upon the foregoing Experiments.
1. In Plants of the same kind, the less they are in Bulk, the smaller the Quantity of the fluid Mass, in which they are set, is drawn off; the Dispendium of it, where the Mass is of equal thickness, being pretty nearly proportion'd to the Bulk, of the Plant. Thus that in the Glass mark'd A, which weigh'd only 27 Grains, drew off but 2558 Grains of the Fluid; and that in B, which weigh'd only 28¼, took up but 3004 Grains; whereas that in H, which weigh'd 127 Grains, spent 14190 Grains of the Liquid Mass.
The Water seems to ascend up the Vessels of Plants, in much the same manner as up a Filtre; and 'tis no great wonder that a larger Filtre should draw off more Water than a lesser; or that a Plant that has more and larger Vessels, should take up a greater share of the Fluid in which it is set, than one that has fewer and smaller ones can. Nor do I note this as a thing very considerable in it self, but chiefly in regard to what I am about to offer beneath; and that it may be seen that, in my other Collations of Things, I made due Allowance for this Difference.
2. The much greatest part of the fluid Mass, that is thus drawn off and convey'd into the Plants, does not settle or abide there; but passes through the pores of them, and exhales up into the Atmosphere. That the Water in these Experiments ascended only through the Vessel of the Plants, is certain. The Glasses F and G, that had no Plants in them, though disposed of in like manner as the rest, remain'd at the End of the Experiment, as at first; and none of the Water was gone off. And that the greatest part of it flies off from the Plant into the Atmosphere, is as certain. The least Proportion of the Water expended, was to the Augment of the Plant, as 46 or 50 to 1. And in some the weight of the Water drawn off, was 100, 200, nay, in one above 700 times as much as the Plant had received of Addition.
This so continual an Emission and Detachment of Water, in so great Plenty from the Parts of Plants, affords us a manifest Reason why Countries that abound with Trees, and the larger Vegetables especially, should be very obnoxious to Damps, great Humidity in the Air, and more frequent Rains, than others that are more open and free. The great Moisture in the Air, was a mighty inconvenience and annoyance to those who first settled in America; which at that time was much overgrown with Woods and Groves. But as these were burnt and destroy'd, to make way for Habitation and Culture of the Earth, the Air mended and clear'd up apace, changing into a Temper much more dry and serene than before.
Nor does this Humidity go off pure and alone; but usually bears forth with it many Parts of the same Nature with those whereof the Plant, through which it passes, consists. The Crasser indeed are not so easily born up into the Atmosphere; but are usually deposited on the Surface of the Flowers, Leaves, and other Parts of the Plants: Hence comes our Manna's, our Honeys, and other Gummous Exsudations of Vegetables. But the finer and lighter Parts are with greater ease sent up into the Atmosphere. Thence they are conveyed to our Organs of Smell, by the Air we draw in Respiration; and are pleasant or offensive, beneficent or injurious to us, according to the Nature of the Plants from whence they arise. And since these owe their Rise to the Water, that ascends out of the Earth through the Bodies of Plants, we cannot be far to seek for the Cause why they are more numerous in the Air, and we find a greater quantity of Odors exhaling from Vegetables, in warm, humid Seasons, than in any other whatever.
3. A great part of the Terrestrial Matter that is mix'd with the Water, ascends up into the Plant as well as the Water. There was much more Terrestrial Matter at the end of the Experiment, in the Water of the Glasses F and G, that had no Plants in them, than in those that had Plants. The Garden-mould dissolved in the Glasses K and L, was considerably diminished, and carried off. Nay, the Terrestrial and Vegetable Matter was born up in the Tubes fill'd with Sand, Cotton, &c. in that Quantity, as to be evident even to Sense. And the Bodies in the Cavities of the other Tubes, that had their lower Ends immers'd in Water, wherein Saffron, Cochinele, &c. had been infused, were tinged with Yellow, Purple, &c.
If I may be permitted to look abroad a while, towards our Shores and Parts within the Verge of the Sea, these will present us with a large Scene of Plants, that, along with the Vegetable, take up into them meer mineral Matter also in great abundance. Such are our Sea-Purslains, the several sorts of Alga's, of Sampires, and other marine Plants. These contain common Sea-salt, which is all one with the Fossil, in such plenty, as not only to be plainly distinguish'd on the Palate, but may be drawn forth of them in considerable Quantity. Nay, there want not those who affirm, there are Plants found that will yield Nitre, and other mineral Salts; of which indeed I am not so far satisfied, that I can depend on the Thing, and therefore give this only as an hint for Enquiry.
To go on with the Vegetable Matter, how apt and how much disposed this, being so very fine and light, is to attend Water in all its Motions, and follow it into each of its Recesses, is manifest, not only from the Instances above alledg'd, but many others. Percolate it withal the Care imaginable: Filter it with never so many Filtrations, yet some Terrestrial Matter will remain. 'Tis true, the Fluid will be thinner every time than other, and more disingaged of the said Matter; but never wholly free and clear. I have filtred Water thorough several wholly free and clear Sheets of thick Paper; and, after that, through very close fine Cloth twelve times doubled. Nay, I have done this over and over; and yet a considerable quantity of this Matter discover'd it self in the Water after all. Now if it thus pass Interstices, that are so very small and fine along with the Water, 'tis the less strange it should attend it in its passage through the Ducts and Vessels of Plants. 'Tis true, filtering and distilling of Water intercepts and makes it quit some of the Earthy Matter it was before impregnated withal: But then that which continues with the Water after this, is fine and light; and such consequently, as is in a peculiar manner fit for the Growth and Nourishment of Vegetables. And this is the Case of Rain-water. The Quantity of Terrestrial Matter it bears up into the Atmosphere, is not great. But that which it does bear up, is mainly of that light kind of Vegetable Matter; and that too perfectly dissolved, and reduced to single Corpuscles, all fit to enter the Tubules and Vessels of Plants: On which Account 'tis, that this Water is so very fertile and prolifick.
The Reason, why in this Proposition, I say, only a great part of the Terrestrial Matter that is mix'd with the Water, ascends up with it into the Plant, is, because all of it cannot. The Mineral Matter is a great deal of it, not only gross and ponderous, but scabrous and inflexible; and so not disposed to enter the Pores of the Roots. And a great many of the simple Vegetable Particles by degrees unite, and form some of them small Clods or Moleculæ; such as those mention'd in H, K, and L, sticking to the Extremities of the Roots of those Plants. Others of them intangle in a looser manner; and form the Nubeculæ, and green Bodies, so commonly observ'd in stagnant Water. These, when thus conjoin'd, are too big to enter the Pores, or ascend up the Vessels of Plants, which singly they might have done. They who are conversant in Agriculture, will easily subscribe to this. They are well aware that, be their Earth never so rich, so good, and so fit for the production of Corn or other Vegetables, little will come of it, unless the Parts of it be separated and loose. 'Tis on this Account they bestow the Pains they do in Culture of it, in Digging, Plowing, Harrowing, and Breaking of the Clodded Lumps of Earth. 'Tis the same way that Sea-salt, Nitre, and other Salts, promote Vegetation. I am sorry I cannot subscribe to the Opinion of those Learned Gentlemen, who imagine Nitre to be essential to Plants; and that nothing in the Vegetable Kingdom is transacted without it. By all the Trials I have been able to make, the thing is quite otherwise; and when contiguous to the Plant, it rather destroys than nourishes it. But this Nitre and other Salts certainly do; they loosen the Earth, and separate the concreted Parts of it; by that means fitting and disposing them to be assumed by the Water, and carried up into the Seed or Plant, for its Formation and Augment. There's no Man but must observe, how apt all sorts of Salts are to be wrought upon by Moisture; how easily they liquate and run with it; and when these are drawn off, and have deserted the Lumps wherewith they were incorporated, those must moulder immediately, and fall asunder of Course. The hardest Stone we meet with, if it happen, as frequently it does, to have any sort of Salt intermix'd with the Sand, of which it consists, upon being expos'd to an humid Air, in a short time dissolves and crumbles all to pieces; and much more will clodded Earth or Clay, which is not of near so compact and solid a Constitution as Stone is. The same way likewise is Lime serviceable in this Affair. The Husbandmen say of it, that it does not fatten, but only mellows the Ground: By which they mean, that it does not contain any thing in it self that is of the same Nature with the Vegetable Mould, or afford any Matter fit for the Formation of Plants; but meerly softens and relaxes the Earth; by that means rendering it more capable of entering the Seeds and Vegetables set in it, in order to their Nourishment, than otherwise it would have been. The Properties of Lime are well known; and how apt 'tis to be put into Ferment and Commotion by Water. Nor can such Commotion ever happen when Lime is mix'd with Earth, however hard and clodded that may be, without opening and loosening of it.
4. The Plant is more or less nourish'd and augmented, in Proportion as the Water, in which it stands, contains a greater or smaller Quantity of proper terrestrial Matter in it. The Truth of this Proportion is so eminently discernable through the whole Process of these Trials, that I think no doubt can be made of it. The Mint in the Glass C, was of much the same Bulk and Weight with those in A and B. But the Water, in which that was, being River-water, which was apparently stored more copiously with terrestrial Matter, than the Spring or Rain-water, wherein they stood, were; it had thriven to almost double the Bulk that either of them had, and with a less Expence of Water too. So likewise the Mint in L, in whose Water was dissolved a small quantity of good Garden-mould, though it had the disadvantage[8] to be less, when first set, than either of the Mints in H or I, whose Water was the very same with this in L, but had none of that Earth mix'd with it; yet, in a short time the Plant not only overtook, but much out-strip'd those and at the end of the Experiment was very considerably bigger and heavier than either of them. In like manner the Mint in N, though less at the beginning than that in M, being set in that thick, turbid, feculent Water, that remained behind, after that wherein M was placed, was still'd off, had in fine more than double its original weight and bulk; and receiv'd above twice the additional Encrease, than that in M, which stood in the thinner distill'd Water, had done. And, which is not less considerable, had not drawn off half the Quantity of Water that that had.
Why, in the beginning of this Article, I limit the Proportion of the Augment of the Plant to the Quantity of proper Terrestrial Matter in the Water, is, because all, even the Vegetable Matter, to say nothing of the Mineral, is not proper for the Nourishment of every Plant. There may be, and doubtless are, some Parts in different Species of Plants, that may be much alike, and so owe their Supply to the same common Matter; but 'tis plain all cannot. And there are other Parts so differing, that 'tis no ways credible they should be formed all out of the same sort of Corpuscles. So far from it, that there want not good Indications, as we shall see by and by, that every kind of Vegetable requires a peculiar and specifick Matter for its Formation and Nourishment. Yea, each Part of the same Vegetable does so; and there are very many and different Ingredients go to the Composition of the same individual Plant. If therefore the Soil, wherein any Vegetable or Seed is planted, contains all or most of these ingredients, and those in due quantity, it will grow and thrive there; otherwise 'twill not. If there be not as many sorts of Corpuscles as are requisite for the Constitution of the main and more essential Parts of the Plant, 'twill not prosper at all. If there be these, and not in sufficient Plenty, 'twill starve, and never arrive to its natural Stature: Or if there be any the less necessary and essential Corpuscles wanting, there will be some failure in the Plant; 'twill be defective in Taste, in Smell, in Colour, or some other way. But though a Tract of Land may happen not to contain Matter proper for the Constitution of some one peculiar kind of Plant; yet it may for several others, and those much differing among themselves. The Vegetative Particles are commix'd and blended in the Earth, with all the diversity and variety, as well as all the uncertainty, conceivable. I have given some intimations of this elsewhere[9], and shall not repeat them here, but hope in due time to put them into a much better Light than that they there stand in.
It is not possible to imagine, how one uniform, homogeneous Matter, having its Principles or Original Parts all of the same Substance, Constitution, Magnitude, Figure, and Gravity, should ever constitute Bodies so egregiously unlike, in all those respects, as Vegetables of different kinds are; nay, even as the different Parts of the same Vegetable. That one should carry a resinous, another a milky, a third a yellow, a fourth a red Juice, in its Veins; one afford a fragrant, another an offensive Smell; one be sweet to the Taste, another bitter, acid, acerbe, austere, &c. that one should be nourishing, another poisonous, one purging, another astringent: In brief, that there should be that vast difference in them, in their several Constitutions, Makes, Properties, and Effects, and yet all arise from the very same sort of Matter, would be very strange. And, to note by the by, this Argument makes equally strong against those, who suppose meer Water the Matter, out of which all Bodies are form'd.
The Cataputia in the Glass E, received but very little Encrease, only three Grains and an half all the while it stood, though 2501 Grains of Water were spent upon it. I will not say the Reason was, because that Water did not contain in it Matter fit and proper for the Nourishment of that peculiar and remarkable Plant. No, it may be the Water was not a proper Medium for it to grow in; and we know there are very many Plants that will not thrive in it. Too much of that Liquor, in some Plants, may probably hurry the Terrestrial Matter thorough their Vessels too fast for them to arrest and lay hold of it. Be that as it will, 'tis most certain there are peculiar Soils that suit particular Plants. In England, Cherries are observ'd to succeed best in Kent; Apples in Herefordshire; Saffron in Cambridgeshire; Wood in two or three of our Midland Counties; and Teazles in Somersetshire. This is an Observation that hath held in all Parts, and indeed in all Ages of the World. The most ancient Writers of Husbandry[10] took notice of it; and are not wanting in their Rules for making choice of Soils suited to the Nature of each kind of Vegetable they thought valuable, or worth propagating.
But, which is a further Proof of what I am here endeavouring to advance, that Soil that is once proper and fit for the Production of some one sort of Vegetable, does not ever continue to be so. No, in Tract of time it loses that Property; but sooner in some Lands, and later in others: This is what all who are conversant in these things know very well. If Wheat, for Example, be sown upon a Tract of Land that is proper for that Grain, the first Crop will succeed very well; and perhaps the second, and the third, as long as the Ground is in Heart, as the Farmers speak; but in a few Years 'twill produce no more, if sowed with that Corn: Some other Grain indeed it may, as Barley. And after this has been sown so often, that the Land can bring forth no more of the same, it may afterwards yield good Oats; and, perhaps, Pease after them. At length 'twill become barren; the Vegetative Matter, that at first it abounded withal, being educed forth of it by those successive Crops, and most of it born off. Each sort of Grain takes forth that peculiar Matter that is proper for its own Nourishment. First, the Wheat draws off those Particles that suit the Body of that Plant; the rest lying all quiet and undisturbed the while. And when the Earth has yielded up all them, those that are proper for Barley, a different Grain, remain still behind, till the successive Crops of that Corn fetch them forth too. And so the Oats and Pease, in their Turn; till in fine all is carried off, and the Earth in great measure drain'd of that sort of Matter.
After all which, that very Tract of Land may be brought to produce another Series of the same Vegetables; but never till 'tis supplied with a new Fund of Matter, of like sort with that it at first contain'd. This Supply is made several ways: By the Grounds lying fallow for some time, till the Rain has pour'd down a fresh Stock upon it: Or, by the Tiller's Care in manuring of it. And for farther Evidence that this Supply is in reality of like sort, we need only reflect a while upon those Manures that are found by constant Experience best to promote Vegetation, and the Fruitfulness of the Earth. These are chiefly either parts of Vegetables, or of Animals; which indeed either derive their own Nourishment immediately from Vegetable Bodies, or from other Animals that do so. In particular, the Blood, Urine, and Excrements of Animals; Shavings of Horns, and of Hoofs; Hair, Wool, Feathers; calcin'd Shells; Lees of Wine, and of Beer; Ashes of all sorts of Vegetable Bodies; Leaves, Straw, Roots, and Stubble, turn'd into the Earth by Plowing or otherwise to rot and dissolve there: These, I say, are our best Manures; and, being Vegetable Substances, when refunded back again into the Earth, serve for the Formation of other like Bodies.
Not wholly to confine our Thoughts to the Fields, let us look a while into our Gardens; where we shall meet with still further Confirmations of the same thing. The Trees, Shrubs, and Herbs cultivated in these, after they have continued in one Station, till they have derived thence the greater part of the Matter fit for their Augment, will decay and degenerate, unless either fresh Earth, or some fit Manure, be applied unto them. 'Tis true, they may maintain themselves there for some time, by sending forth Roots further and further to a great Extent all round, to fetch in more remote Provision; but at last all will fail; and they must either have a fresh Supply brought to them, or they themselves be removed and transplanted to some Place better furnished with Matter for their Subsistence. And accordingly Gardiners observe, that Plants that have stood a great while in a Place, have longer Roots than usual; part of which they cut off, when they transplant them to a fresh Soil, as now not of any further use to them. All these Instances, to pass over a great many others that might be alledg'd, point forth a particular Terrestrial Matter, and not Water, for the Subject to which Plants owe their Increase. Were it Water only, there would be no need of Manures; or of transplanting them from place to place. The Rain falls in all Places alike; in this Field and in that indifferently; in one side of an Orchard or Garden, as well as another. Nor could there be any Reason, why a Tract of Land should yield Wheat one Year, and not the next; since the Rain showers down alike in each. But I am sensible I have carried on this Article to too great a length; which yet on so ample and extensive a Subject, 'twas not easie to avoid.
5. Vegetables are not form'd of Water; but of a certain peculiar Terrestrial Matter. It hath been shewn, that there is a considerable Quantity of this Matter contain'd both in Rain, Spring, and River-water: That the much greatest part of the fluid Mass that ascends up into Plants, does not settle or abide there, but passes through the Pores of them, and exhales up into the Atmosphere; That a great part of the Terrestrial Matter, mix'd with the Water, passes up into the Plant along with it; and that the Plant is more or less augmented in proportion, as the Water contains a greater or smaller Quantity of that Matter. From all which we may very reasonably infer, that Earth, and not Water, is the Matter that constitutes Vegetables. The Plant in E, drew up into it 2501 Grains of the fluid Mass; and yet had received but Grains 3 and a half of Increase from all that. The Mint in L, though it had at first the disadvantage to be much less than that in I; yet being set in Water wherewith Earth was plentifully mix'd, and that in I, only in Water without any such additional Earth, it had vastly outgrown the other, weighing at last 145 Grains more than that did, and so having gain'd about twice as much as that had. In like manner that in K, though 'twas a great deal less when put in than that in I, and also was impair'd and offended by Insects; yet being planted in Water wherein Earth was dissolved, whereas the Water in which it stood had none, it not only over-took, but considerably surpass'd the other; weighing at last 29 Grains more than that in I, and yet had not expended so much Water as that, by above 2400 Grains. The Plant in N, tho' at first a great deal less than that in M; yet being set in the foul crass Water that was left in the Still, after that, in which M was set, was drawn off, in Conclusion had gain'd in weight above double what that in the finer and thinner Water had. The Proportion of the Augment of that Plant that throve most was, to the fluid Mass spent upon it, but as 1 to 46. In others, 'twas but as 1 to 60, 100, 200; nay, in the Cataputia, 'twas but as 1 to 714. The Mint in B took up 39 Grains of Water a-day, one day with another; which was much more than the whole weight of the Plant originally; and yet, with all this, it gain'd not one fourth of a Grain a-day in weight. Nay, that in H took up 253 Grains a day of the Fluid: Which was near twice as much as its original Weight, it weighing, when first set in the Water, but 127 Grains. And, after all, the daily Encrease of the Plant was no more than Grains 215⁄56.
6. Spring, and Rain-water, contain pretty near an equal Charge of Vegetable Matter; River-water more than either of them. The Plants in the Glasses A, B, and C, were at first of much the same size and weight. At the End of the Experiment, the Mint in A had gain'd 15 Grains out of 2558 Grains of Spring-water; that in B, Grains 17 and an half, out of 3004 Grains of Rain-water; but that in C had got 26 Grains out of only 2493 Grains of River-water. I do not found this Proposition solely upon these Trials; having made some more, which I do not relate here, that agree well enough with these. So that the Proportions here deliver'd, will hold for the main; but a strict and just Comparison is hardly to be expected. So far from it, that I make no doubt, but the Water that falls in Rain, at some times, contains a greater share of Terrestrial Matter than that which falls at others. A more powerful and intense Heat must needs hurry up a larger quantity of that Matter along with the humid Vapours that form Rain, than one more feeble and remiss ever possibly can. The Water of one Spring may flow forth with an higher Charge of this Matter, than that of another; this depending partly upon the quickness of the Ebullition of the Water, and partly upon the Quantity of that Matter latent in the Strata, through which the Fluid passes, and the greater or less laxity of those Strata. For the same Reason, the Water of one River may abound with it more than that of another. Nay, the same River, when much agitated, and in commotion, must bear up more of it, than when it moves with less rapidity and violence. That there is a great Quantity of this Matter in Rivers; and that it contributes vastly to the ordinary Fertility of the Earth, we have an illustrious Instance in the Nile, the Ganges, and other Rivers that yearly overflow the neighbouring Plains. Their Banks shew the fairest and largest Crops of any in the whole World. They are even loaded with the multitude of their Productions; and those who have not seen them, will hardly be induced to believe the mighty Returns those Tracts make in comparison of others, that have not the Benefit of like Inundations.
7. Water serves only for a Vehicle to the Terrestrial Matter, which forms Vegetables; and does not it self make any addition unto them. Where the proper Terrestrial Matter is wanting, the Plant is not augmented, though never so much Water ascend into it. The Cataputia in E, took up more Water than the Mint in C, and yet had grown but very little, having received only three Grains and an half of additional weight; whereas the other had received no less than twenty six Grains. The Mint in I, was planted in the same sort of Water as that in K, was; only the latter had Earth dissolved in the Water; and yet that drew off 13140 Grains of the Water, gaining it self no more than 139 Grains in weight; whereas the other took up but 10731 Grains of the Water, and was augmented 168 Grains in weight. Consequently that spent 2409 Grains more of the Water than this in K, did, and yet was not so much encreased in weight as this by 29 Grains. The Mint in M, stood in the very same kind of Water as that in N, did. But the Water in M, having much less Terrestrial Matter in it than that in N had, the Plant bore up 8803 Grains of it, gaining it self only 41 Grains the while; whereas that in N drew off no more than 4344 Grains, and yet was augmented 94 Grains. So that it spent 4459 Grains of Water more than that did; and yet was not it self so much increased in weight, as that was, by 53 Grains. This is both a very fair, and a very conclusive Instance; on which Account 'tis that I make oftner use of it. Indeed they are all so; and to add any thing further on this Head, will not be needful.
'Tis evident therefore Water is not the Matter that composes Vegetable Bodies. 'Tis only the Agent that conveys that Matter to them; that introduces and distributes it to their several Parts for their Nourishment. That Matter is sluggish and unactive, and would lie eternally confin'd to its Beds of Earth, without ever advancing up into Plants, did not Water, or some like Instrument, fetch it forth and carry it unto them. That therefore there is that plentiful Provision, and vast Abundance of it supplied to all Parts of the Earth, is a mark of a natural Providence superintending over the Globe we inhabit; and ordaining a due Dispensation of that Fluid, without the Ministry of which the Noble Succession of Bodies we behold, Animals, Vegetables, and Minerals, would be all at a stand[11]. But to keep to Plants, 'tis manifest Water, as well on this, as upon the other Hypothesis, is absolutely necessary in the Affair of Vegetation; and it will not succeed without it: Which indeed gave occasion to the Opinion, that Water it self nourished, and was changed into Vegetable Bodies. They saw, though these were planted in a Soil never so rich, so happy, so advantageous, nothing came of it unless there was Water too in a considerable quantity. And it must be allow'd Vegetables will not come on or prosper where that is wanting: But yet what those Gentlemen inferr'd thence, was not, we see, well grounded.
This Fluid is capacitated for the Office here assign'd it several ways: By the Figure of its Parts, which, as appears from many Experiments, is exactly and mathematically Spherical; their Surfaces being perfectly polite, and without any the least Inequalities. 'Tis evident, Corpuscles of such a Figure are easily susceptible of Motion, yea, far above any others whatever; and consequently the most capable of moving and conveying other Matter, that is not so active and voluble. Then the Intervals of Bodies of that Figure are, with respect to their Bulk, of all others the largest; and so the most fitted to receive and entertain foreign Matter in them. Besides, as far as the Trials hitherto made inform us, the constituent Corpuscles of Water are, each singly consider'd, absolutely solid; and do not yield to the greatest External Force. This secures their Figure against any Alteration; and the Intervals of the Corpuscles must be always alike. By the latter, 'twill be ever disposed to receive Matter into it; and by the former, when once received, to bear it on along with it. Water is further capacitated to be a Vehicle to this Matter, by the tenuity and fineness of the Corpuscles of which it consists. We hardly know any Fluid in all Nature, except Fire, whose constituent Parts are so exceeding subtle and small as those of Water are. They'll pass Pores and Interstices, that neither Air nor any other Fluid will. This enables them to enter the finest Tubes and Vessels of Plants, and to introduce the Terrestrial Matter, conveying it to all Parts of them; whilst each, by means of Organs 'tis endowed with for the Purpose, intercepts and assumes into it self such Particles as are suitable to its own Nature, letting the rest pass on through the common Ducts. Nay, we have almost every where Mechanical Instances of much the same Tenor. 'Tis obvious to every one, how easily and suddenly Humidity, or the Corpuscles of Water sustained in the Air, pervade and insinuate themselves into Cords, however tightly twisted, into Leather, Parchment, Vegetable Bodies, Wood, and the like. This it is that fits them for Hygrometers; and to measure and determine the different quantities of Moisture in the Air, in different Places and Seasons. How freely Water passes and carries with it Terrestrial Matter, through Filtres, Colatures, Distillations, &c. hath been intimated already.
8. Water is not capable of performing this Office to Plants, unless assisted by a due Quantity of Heat; and this must concur, or Vegetation will not succeed. The Plants that were set in the Glasses Q, R, S, &c. in October, and the following colder Months, had not near the quantity of Water sent up into them, or so great an additional Encrease by much, as those that were set in June, July, and the hotter. 'Tis plain Water has no power of moving it self; or rising to the vast height it does in the more tall and lofty Plants. So far from this, that it does not appear from any Discovery yet made, that even its own Fluidity consists in the intestine Motion of its Parts; whatever some, otherwise very learned and knowing, Persons may have thought. There is no need of any thing more, for solving all the Phænomena of Fluidity, than such a Figure and Disposition of the Parts, as Water has. Corpuscles of that make, and that are all absolutely Spherical, must stand so very tickle and nicely upon each other, as to be susceptible of every Impression; and though not perpetually in Motion, yet must be ever ready and liable to be put into it, by any the slightest Force imaginable. It is true, the Parts of Fire or Heat are not capable of moving themselves any more than those of Water; but they are more subtil, light, and active, than those are, and so more easily put into Motion. In fine, 'tis evident and matter of Fact, that Heat does operate upon, and move the Water, in order to its carrying on the Work of Vegetation: But how 'tis agitated it self, and where the Motion first begins, this is no fit Place to enquire.