Chapter VIII: Appendix (7)

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.

[Sidenote: _De Respirationis Organis & Usu._]

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. 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.

[Sidenote: Boyle _of the Elasticity of Air. Pechlinus de Aeris & Alimenti defectu._]

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 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 170-8/15 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 171-22/35 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 95-23/26 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 65-3/57 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 714-4/7 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._