The third Particular which later Discoveries make probable, is, that Animals cannot be formed of these Animalcula without the Ova in fœminis, which are necessary for supplying of them with proper Nutriment: And this these Considerations seem to evince. 1. It is probable that an Animalcle cannot come forward, if it do not fall into a proper Nidus. This we see is the Cicatricula in Eggs; and tho' a Million of them should fall into an Egg, none of them would come forward, but what were in the Center of the Cicatricula; and perhaps the Nidus necessary for their formation is so proportion'd to their bulk, that it can hardly contain more than one Animalcle; and this may be the reason why there are so few Monsters. This we see is absolutely necessary in Oviparis; and the only difference which seems to be between them and the Vivipara, in this matter, is in this, that in the latter the Ova are properly nothing more but the Cicatricula, with its Colliquamentum, so that the Fœtus must spread forth its Roots into the Uterus to receive its nourishment; but the Eggs in Oviparis may be properly term'd an Uterus, in relation to the Fœtus; for they contain not only the Cicatricula, with its Amnion and the Colliquamentum, which is the immediate nourishment of the Fœtus, but also the materials which are to be converted into that Colliquamentum; so that the Fœtus spreads forth its Roots no farther than into the White and Yolk of the Egg, from whence it derives all its nourishment. Now that an Animalcle cannot come forward without some such proper Nidus, Mr. Leewenhoeck will not readily deny; for if there were nothing needful, but their being thrown into the Uterus, I do not see why many hundreds of them should not come forward at once; for as to what Mr. Leewenhoeck says, that one of them would be-dwarf and choak the rest; this might fall out in process of time: But at first I do not see why many of them should not grow together, whilst scatter'd in so large a Field (and yet no such thing is observed) if there were not an absolute necessity of a Cicatricula for their growth and thriving. Now, 2. That this Cicatricula is not originally in Utero, seems evident from the frequent Conceptions which have been found extra Uterum: Such as the Child which continued Twenty six Years in the Woman of Tholouse's Belly, mention'd Numb. 139. of the Philos. Trans. And the little Fœtus found in the Abdomen de St. Mere, together with the Testicle torn and full of clotted Blood, recorded Numb. 150. both taken out of the Journals des Savans: Such also seem to be the Fœtus in the Abdomen of the Woman of Copenhagen, mention'd in the Nouvelles des Lettres, for Sept. 85. pag. 996. all the Members of which were easily to be felt through the Skin of the Belly, and which she had carried in her Belly for four Years; and the seven Years Gravidation, related by Dr. Cole, Numb. 172. of the Transact. That these two were undoubtedly extra Uterum, is uncertain, because the last was not open'd after her death, and the former may be yet still alive. Now granting once the necessity of a proper Nidus, for the formation of an Animalcle into the Animal of its respective kind; these Observations make it probable, that the Testes are the Ovaria appropriated for this use; for tho' the Animalcles coming thither in such Cases may seem to be extraordinary, and that usually the Impregnation is in Utero; yet it may be collected from hence, that the Cicatriculæ or Ova to be impregnated, are in Testibus fœmineis; for if it were not so, the accidental coming of Animalcles thither could not make them come forward more than in any other part of the Body, since they cannot be formed and nourished without a proper Nidus. But 3. It is acknowledg'd by all, that the Fœtus in Utero, for some considerable time after Conception, has no connexion with the Womb, that it sits wholly loose to it, and is perfectly a little round Egg with the Fœtus in the midst, which sends forth its Umbilical Vessels by degrees, and at last lays hold on the Uterus. Now from hence it seems evident, that the Cicatricula, which is the Fountain of the Animalcles nourishment, does not sprout from the Uterus, but has its Origin elsewhere, and falls in thither as into a fit Soil, from whence it may draw Nutriment for the growth of the Fœtus, else it cannot be easily imagin'd, how it should not have an immediate Connexion with the Uterus from the time of Conception. If you join all these three Considerations together, viz. that an Animalcle cannot come forward without a proper Nidus or Cicatricula; that there have been frequent Fœtus's extra Uterum; and that they have no Adhæsion to the Uterus, for a considerable time after Conception, they seem to make it evident, that Animals cannot be form'd ex Animalculis without the Ova in Fœminis. To all these I shall subjoin the Proposal of an Experimentum Crucis, which may seem to determine, whether the Testes Fœmineæ be truly the Ovaria, viz. Open the Abdomen of the Females of some kinds, and cut out these Testicles, and this will determine, whether they be absolutely necessary for the formation of Animals.
There are some Difficulties proposed against this Conjecture, which I think may be easily resolved. Some object the distance between the Tubæ or Cornua Uteri, and the Testicles; but to this is opposed by Swammerdam, and others, the like distance between the Infundibulum, in Hens and Frogs, and the Ovary; and yet it cannot be denied that the Eggs are transmitted thro' this into the Uterus: And besides R. de Graef, and others, have by repeated Observations found that the Cornua Uteri do at certain times after Conception, embrace the Testes on both sides the Uterus. They object in the second place the great disproportion between the pretended Eggs in the Ovary, and the Aperture of the Tubæ or Cornua Uteri, the former being a great deal bigger than the latter: But both R. de Graef and Malpighius have clear'd that Matter, by making appear, that these Bladders in the Ovary are not the Ova, but serve to form the Glandules within which the Ova are formed, which break through a small Papilla opening in the Glandule, which bears a proportion to the Aperture of the Tube. They object 3, The difficulty to conceive how these Eggs should be impregnated per semen Maris, both because there is no Connexion between the Tubæ and the Ovary for its transmission, and for that Dr. Harvey could never discover any thing of it in Utero. As to the last, Mr. Leewenhoeck has cleared that difficulty, by the discovery of innumerable Animalcula Seminis Maris in Cornubus Uteri, and those living a considerable time after Coition. Numb. 174. of the Transact. And as to the former, we may either suppose that there is such an Inflation of the Tubæ or Cornua Uteri tempore Coitionis, as makes them embrace the Ovaria, and such an approach of the Uterus and its Cornua, as that I may easily transmit the Seed into the Ovary; or else, that the Ova are impregnated by the Animalcles after they descend into the Uterus, and not in the Ovary; the former seems probable for this Reason, that at least a whole Cluster of Eggs in a Hen will be fecundated by one Tread of the Cock: Now this Fecundation seems to be in the Vitellary, and not in the Uterus, as the Eggs pass along from day to day; for it can hardly be supposed that the Animalcles should subsist so long, being scattered loosely in the Uterus, as to wait there for many days for the Fecundation of the Eggs as they pass along. The latter Conjecture has this to strengthen it, that the Animalcles are found to live a considerable time in the Uterus; and that if they should impregnate the Ova in the Ovary it self, the Fœtus would increase so fast, that the Ova could not pass through the Tubæ Uteri, but would either burst the Ovary, or fall down into the Abdomen from the Orifices of the Tubæ; and that from hence proceed those extraordinary Conceptions in Abdomine extra Uterum. But, 4. Mr. Leewehoeck, Numb. 147. of the Transact. to weaken the third Consideration about the Conceptions, being like unto an Ovum in the Womb, proposes a Parallel between these Animalcles and Insects; and insinuates, that as the latter cast their Skins, and appear of another Shape, so the other which at first seem like Tadpoles, may cast their outer Skin, and then be round; and that this may be the occasion of the round Figure of the Conception in the Womb. To this it may be replied, that according to Mr. Leewenhoeck's own Sentiment, the Animalcles cannot come forward, if they do not find the Punctum or proper place for their Nourishment, to which it seems they must have some Adhæsion. Now the Conception in Viviparis is not fastned unto the Womb for many days, nor does adhere to any point of it; so that it seems this roundish Body is not the Animalcle thus chang'd after having cast an outer Skin, but is rather the Cicatricula or little Egg, into which the Animalcle has entred as its Punctum or place of nourishment; else I do not see why they should not be adhering to the Womb from the first Conception, or why (as I have said) many hundreds of them are not conceiv'd and formed together, &c.
A short Discourse concerning Concoction: Read at a Meeting of the Royal Society, May ... 1699, by Clopton Havers, M. D. Fellow of the Royal Society.
THE manner in which the Digestion of the Aliment is performed, is a thing not very easie to be understood and explained. However, it has not escap'd the Conjectures of some Philosophical Men, who having curiously observ'd the Phænomena of Nature, and enquired into their Causes, have, amongst other things, endeavour'd to account for this. But their Sentiments about it have been various, and the Hypothesis, by which they have studied to explain it, very different. Some have thought the Concoction of the Food to be a kind of Elixation; and that the grosser and more solid Parts being, as it were, boil'd in the Liquid by the Heat of the Stomach, and the Parts adjacent to it, as the Liver, Spleen, and Omentum, are by a long and continued Elixation, first render'd more tender, and then colliquated, and dissolved into minuter Particles, so as to mix more equally with the Fluid, and with that to make one Pulpament, or chylous Mass. And Hippocrates, tho' he does not plainly call it an Elixation, yet seems to attribute the Concoction of the Food to the Heat of the Stomach, as the Cause of it, Sect. 4. Libro de salubri victus ratione. So where he takes notice of the voiding of such Fæces, as appear to be like the Food that has been eaten; he adds, Constat enim, sane ventriculum, ciborum copiam, ut concoquat, calefacere non posse. And there are other Passages in the same Book, from which we may conclude, that he suppos'd the Heat of the Stomach to be the great Cause of the Digestion of the Food.
There are others that make the Stomach itself to be the great Instrument of Digestion, but in a different manner: And they suppose it to be perform'd by an Attrition, as if the Stomach, by those repeated Motions, which are the necessary Effects of Respiration, when it is distended by the Aliment, did both rub or grind off some minuter Particles from the grosser Parts; and by continually agitating the Mass of Food, make those Parts, which are not contiguous to the Stomach, strike one against another, and break one another in pieces, until they are all attenuated. It is evident enough, that the sides of the Stomach do in Expiration press upon the Contenta, so as to oblige, at least some Parts of them, every time the Muscles of the Abdomen are contracted, to move and shift their places. So in Inspiration, when the Diaphragm and Liver press upon the upper part of the Stomach, the Aliment must be moved again. So that by these reciprocal Motions, that part of the Food which is contiguous to the Stomach, and moves in a Line parallel to it, must rub against it; and all the other Parts being moved by such a Compression, as gives them a different Tendency, it is certain they must be continually striking one against another. And for Bread, and such things as are made of Flower, that will be softned and dissolv'd with any common Liquid, that Agitation of the Stomach which moves them in Respiration, might seem sufficient to break and dissolve them, when they are sufficiently moisten'd with a Fluid. Yet this cannot be thought enough to break and digest Flesh-meat, Fruits, or any other thing that will not be softned and dissolv'd in Water, or some such Liquid. But although this Motion of the Aliment, caused by Respiration, does not actually digest it, yet it has a great and necessary Use in Concoction, and makes all the grosser Parts, as they are attenuated, mix equally with the Fluid.
Some think that the Bilious Juice; others, that the Spirits are chiefly concern'd in this Affair. Galen, in his Book de Neutralibus Facultatibus, makes it to be the Effect, not of one, but of several Causes; as a pituitous Juice in the Stomach, the Bile, &c. which appears from what he has said, and the Translator thus render'd: 'Verum quanto ii (cibi) qui mansi sunt, iis, qui inhæserunt, magis sunt alterati; tanto etiam his magis ii, qui devorati sunt. Siquidem incomparabilis erit horum alterationis excessus, si & quæ in ventre est Pituita & Bilis, & Spiritus, & Calor, & tota Ventris substantia, æstimentur.'
Some there are that will have the Food to be dissolv'd by a Menstruum, which is supply'd from the Glands of the Stomach, or some other way: But those that do so far agree in the General, as to think Concoction is perform'd by a Dissolvent, do differ in their Notions of the Nature of the Menstruum: For there are some that suppose it to be an Acid, which does erode the grosser parts of the Food, and dissolves them in the same manner as Vinegar, Spirit of Vitriol, or any such-like Acid, will dissolve even so solid a Body as Iron. And it cannot be deny'd, but that Oil of Vitriol will dissolve Flesh-meat, and reduce it to a Pulp; but it is not to be suppos'd, that the Fibres of the Stomach can admit any such strong and corroding Acid, without something to correct it, but it must be injur'd in its Tone, and labour under great and extraordinary Pains. Neither does such a Menstruum, tho' it will digest some things, seem capable of dissolving so great a Variety of Things as we eat, especially when a great many of them are of a contrary Nature. Some will have the Menstruum to be a nitro-aerius Spirit, that is, quick, and very penetrating, and included in its proper Vehicle; which, being in its own Nature apt to penetrate the Mass of the Aliment, does diffuse it self through the Whole, and breaking the Vinculum of the more solid Parts, does dissolve their Compages. By others, it is thought to be some saline Juice in the Stomach, by which the Parts of the Aliment are divided and dissolved, and those which are fit for Nourishment, are volatiliz'd.
Lastly, There are some others who reject the Opinions I have already mention'd, and suppose the Digestion of the Food to be perform'd by the Benefit of a Ferment; which, when it is mixed with the Aliment, excites in the Mass an intestine motion; and the different and contrary motions and tendency of the Parts, making some kind of Collision, gradually break off Particles from the grosser, and more solid Parts, till they are so attenuated as to be apt to mix more equally with the Fluid, and with them to make one soft or chylous Substance. But yet there is not amongst them an universal Consent, either about the Nature of this Ferment, or the manner how it is supply'd. For first, some think it to be the Remains of the Food that was last digested; which having lain some time in the Stomach, after the rest is carried down into the Intestines, contracts an Acid, or some other Quality, and is so alter'd, as to partake of the Nature of a Leaven. And this Leaven being a part of the Food, which has been already digested, is so soft and liquid as to be capable of mixing with the Aliment, which is next taken into the Stomach; and being agitated with it by the repeated Pressures of the Diaphragm, Liver, and Abdominal Muscles upon the Stomach in Respiration, does diffuse it self through the whole Mass; and being mixed with it, like Leaven, or Yest added to new Wort, &c. puts it into a State of Fermentation; and by this Fermentation, or the Expansion of the Ferment, and the more tenuious Parts, which are first put into motion by it, those which are more solid, and with which they are intermixed, are rent, and divided, and so attenuated, as to become a soft and pulpous matter. And altho' the greatest part of the Food, that is thus broken and concocted, is by the Contraction of the Fibres of the Stomach press'd into the Duodenum; yet they do not contract themselves so as to force out all the Aliment, but leave between the Rugæ or Folds, on the inside of the Stomach, a sufficient Quantity to be a Leaven to the next Meal; and so from time to time.
Some have a Notion, That this Ferment, or Principle of Fermentation, is in the Aliment it self; which being a Congeries of Matter, consisting of various Parts of a different Nature, is no sooner enclosed in the Stomach, and digested in the Heat of that, and the adjacent Parts, but the more spirituous and subtil Particles are put into motion both from that Warmth, and the difference of their Natures, and enter upon a Fermentation. And so by their intestine Commotion, and the Violence they offer to those Parts which oppose the tendency of any of them, they break and dissolve what is more solid.