Reflections upon Ancient and Modern Learning/Chapter 17
CHAP. XVII.
Of Ancient and Modern Anatomy.
ANatomy is one of the most necessary Arts to open to us Natural Knowledge of any that was ever thought of. Its Usefulness to Physicians was very early seen; and the Greeks took great Pains to bring it to Perfection. Some of the first Dissectors (q)(q) Corn. Celsus in Præfatione. tried their Skill upon living Bodies of Men, as well as Brutes. This was so inhumane and barbarous a Custom, that it was soon left off: And it created such an Abhorrence in Mens Minds of the Art it self, that in Galen's Time even dead Bodies were seldom opened; and he was often obliged (r)(r) Anat. Administrat. passim. to use Apes instead of Men, which sometimes led him into great Mistakes.
It may be said, perhaps, that because there is not an ancient System of Anatomy extant, therefore the Extent of their Knowledge in this particular cannot be known. But the numerous Anatomical Treatises of Galen do abundantly supply that Defect. In his elaborate Work of the Uses of the Parts of Humane Bodies, he gives so full an Idea of ancient Anatomy, that if no other ancient Book of Anatomy were extant, it alone would be sufficient for this purpose. He is very large in all his Writings of this Kind, in taking Notice of the Opinions of the Anatomists that were ancienter than himself, especially when they were mistaken, and had spent much Time and Pains in opening Bodies of Brutes, of which he somewhere promises to write a comparative Anatomy. So that his Books not only acquaint us with his own Opinions, but also with the Reasonings and Discoveries of Hippocrates, Aristotle, Herophilus and Erasistratus, whose Names were justly venerable for their Skill in these things. Besides, he never contradicts any Body without appealing to Experience, wherein though he was now and then mistaken, yet he does not write like a Pedant, affirming a thing to be true or false upon the Credit of Hippocrates, or Herophilus, but builds his Argument upon Nature as far as he knew her. He had an excellent Understanding, and a very piercing Genius, so that the false uses which he very frequently assigns to several Parts, do certainly shew that he did not understand the true Texture of those Parts, because where his Anatomy did not fail him, his Ratiocinations are, generally speaking, exact. Wherefore in this particular his Mistakes instruct us as effectually in the Ancients Ignorance, as his true Notions do in their Knowledge. This will appear at large hereafter, where it will be of mighty use to prove, That the Ancients cannot be supposed to have known many of the most eminent Modern Discoveries, since if they had known them, they would not have assigned such Uses to those Parts, as are not reconcilable to those Discoveries. If Galen had known that the Pancreas had been a Heap of small Glands, which all emit into one common Canal, a particular Juice carried afterwards through that Canal into the Guts; which there meeting with the Bile goes forwards, and assists it in the making of the Chyle, he would never have said (s)(s) De usu Partium, lib. V. cap. 2. that Nature made it for a Pillow to support the Veins; which go out of the Liver in that Place, where they divide into several Branches, lest if they had been without a Rest, they should have been hurt by the violent Eruption of the Blood; and this too without the assigning any other Use for it.
By Anatomy there is seldom any thing understood but the Art of laying open the several Parts of the Body with a Knife, that so the Relation which they severally bear each to other may be clearly discerned. This is generally understood of the containing Parts, Skin, Flesh, Bones, Membranes, Veins, Arteries, Muscles, Tendons, Ligaments, Cartilages, Glands, Bowels, wherein only the Ancients busied themselves: As for the Examination of the Nature and particular Texture of the contained Parts, Blood, Chyle, Urine, Bile, Serum, Fat, Juices of the Pancreas, Spleen and Nerves, Lympha, Spittle, Marrow of the Bones, Mucilages of the Joints, and the like; they made very few Experiments, and those too for want of Chymistry very imperfect. The Discoveries therefore which have been made in that nobler part, which are numerous and considerable, are in a manner wholly owing to later Ages. In the other, a great deal was anciently done, though a great deal more was left for Posterity to do.
I shall begin with the Body in general. It is certain that all the great Divisions of the Bones, Muscles, Veins and Arteries; most of the visible Cartilages, Tendons and Ligaments, were very exactly known in Galen's Time; the Positions of the Muscles, their several Originations, the Insertions of their Tendons, and investing Membranes, were, for the most part, traced with great Nicety and Truth; the more conspicuous pairs of Nerves which arise either from the Brain or Spinal Marrow, were very well known and carefully followed; most of the great Branches of the Veins and Arteries; almost all the Bones and Cartilages, with very many Muscles, have still old Greek Names imposed upon them by the Old Anatomists, or Latin Names translated from the Greek ones: So that, not only the easie things and such as are discernable at first Sight, were throughly known; but even several particulars, especially in the Anatomy of Nerves, were discovered, which are not obvious without great Care, and a good deal of practical Skill in diffecting. So much in general; from which it is evident, that as far as Anatomy is peculiarly useful to a Chirurgeon, to inform him how the Bones, Muscles, Blood-Vessels, Cartilages, Tendons, Ligaments and Membranes lie in the Limbs and more conspicuous Parts of the Body, so far the Ancients went: And here, there is very little that the Moderns have any Right to pretend to as their own Discoveries; though any Man, that understands these things, must own, That these are the first things which offer themselves to an Anatomist's View.
Here I shall beg Leave to descend to Particulars, because I have not seen any Comparison made between Ancient and Modern Anatomy, wherein I could acquiesce; whilst some, as Mr. Glanvile (t)(t) Essay of Modern Improvements of useful Knowledge., and some others who seem to have copied from him, have allowed the Ancients less than was their Due; others, as Vander Linden and Almeloveen (u)(u) Inventa Nov. Antiqua., have attributed more to them than came to their Share; especially since (though perhaps it may be a little tedious, yet) it cannot be called a Digression.
Hippocrates (w)(w) De Glandulis pag 148. §. 7. Edit. Vander Linden. took the Brain to be a Gland. His Opinion was nearer to the Truth than any of his Successors; but he seems to have thought it to be a similar Substance, which it evidently is not. And therefore, when several Parts of it were discovered not to be glandulous, his Opinion was rejected. Plato took it to be Marrow, such as nourishes the Bones; but its Weight and Texture soon destroyed his Notion, since it sinks in Water wherein Marrow swims; and is hardned by Fire, by which the other is melted. Galen (x)(x) De usu Parrium, lib. VIII. cap. 6. saw a little farther, and he asserts it to be of a nervous Substance, only something softer than the Nerves in the Body. Still they believed that the Brain was an uniform Substance, and as long as they did so, they were not like to go very far. The first Anatomist who discovered the true Texture of the Brain was Archangelus Piccolhomineus (y)(y) Malpighius Epist. de Cerebro ad Fracassatum, p. 2. an Italian, who lived in the last Age. He found that the Brain properly so called, and Cerebellum, consist of Two distinct Substances, an outer Ash-coloured Substance, through which the Blood-Vessels which lie under the Pia Mater in innumerable Folds and Windings, are disseminated; and an inner every where united to it, of a nervous Nature, that joins this Bark (as it is usually called) to the Medulla Oblongata, which is the Original of all the Pairs of Nerves that issue from the Brain, and of the Spinal Marrow, and lies under the Brain and Cerebellum. After him Dr. Willis (z)(z) Anat. Cerebri. was so very exact, that he traced this medullar Substance through all its Insertions into the Cortical, and the Medulla Oblongata, and examined the Rises of all the Nerves, and went along with them into every Part of the Body with wonderful Curiosity. Hereby not only the Brain was demonstrably proved to be the Fountain of Sense and Motion, but also by the Courses of the Nerves, the Manner how every Part of the Body conspires with any others to procure any one particular Motion, was clearly shewn; and thereby it was made plain even to Sense, that where-ever many parts joined at once to cause the same Motion, that Motion is caused by Nerves that go into every one of those Parts, which are all struck together. And though Vieussens and du Verney have in many things corrected Dr. Willis's Anatomy of the Nerves; yet they have strengthened his general Hypothesis, even at the Time when they discovered his Mistakes, which is the same thing to our present purpose. Galen, indeed (a),(a) De V. P. l. 8. c. 4. had a right Notion of this matter, but he traced only the larger Pairs of Nerves, such as could not escape a good Anatomist.
But the manner of the forming of the Animal Spirit in the Brain was wholly unknown. In Order to the Discovery whereof, Malpighius (b)(b) De Cerebri Cortice. by his Microscopes found that the Cortical Part of the Brain consists of an innumerable Company of very small Glandules, which are all supplied with Blood by Capillary Arteries; and that the Animal Spirit, which is separated from the Mass of the Blood in these Glandules, is carried from them into the Medulla Oblongata through little Pipes, whereof one belongs to every Gland, whose other End is inserted into the Medulla Oblongata, and that these Numberless Pipes, which in the Brain of some Fishes look like the Teeth of a small Ivory Comb (c)(c) De Cerebro, pag. 4., are properly that which all Anatomists after Piccolhomineus have called the Corpus callosum, or the Medullar Part of the Brain. This Discovery destroys the Ancient Notions of the Uses of the Ventricles of the Brain, and makes it very probable that those Cavities are only Sinks to carry off excrementitious Humours, and not Store-Houses of the Animal Spirit: It shews likewise how little they knew of the Brain who believed that it was an uniform Substance. Some of the Ancients disputed (d)(d) Galen de V. P. l. 8. c. 2. whether the Brain were not made to cool the Heart. Now though these are ridiculed by Galen, so that their Opinions are not imputable to those who never held them; yet they shew that these famous Men had examined these things very superficially: For no Man makes himself ridiculous if he can help it; and now, that Mankind are satisfied by ocular Demonstration that the Brain is the Original of the Nerves, and the Principle of Sense and Motion, he would be thought out of his Wits that should doubt of this Primary use of the Brain, though formerly when things had not been so experimentally proved, Men might talk in the dark, and assign such Reasons as they could think of, without the Suspicion of being ignorant or impertinent.
The Eye is so very remarkable a Member, and has so many Parts peculiar to its self, that the Ancients took great Notice of it. They found its Humours, the watry, crystalline, and glassy, and all its Tunicles, and gave a good Description of them; but the Optick Nerve, the aqueous Ducts which supply the watry Humour, and the Vessels which carry Tears were not enough examined. The first was done by Dr. Briggs (e),(e) Theory of Vision. Grew's Transact. numb. 6, and Philos. Transact. numb. 147. who has found that in the Tunica Retiformis, which is contiguous to the glassy Humour, the Filaments of the Optick Nerve there expanded, lie in a most exact and regular Order, all parallel one to another, which when they are united afterwards in the Nerve are not shuffled confusedly together, but still preserve the same Order till they come to the Brain. The crystalline Humour had already been discovered to be of a Double-Convex Figure, made of Two unequal Segments of Spheres, and not perfectly spherical as the Ancients thought. So that this further Discovery made by Dr. Briggs, shews evidently why all the Parts of the Image are so distinctly carried to the Brain, since every Ray strikes upon a several Filament of the Optick Nerve, and all those strings so struck are moved equably at the same Time. For want of knowing the Nature and Laws of Refraction, which have been exactly stated by Modern Mathematicians, the Ancients discoursed very lamely of Vision. This made Galen think that the crystalline Humour (f)(f) De usu Partium, lib. VIII. cap. 6. was the Seat of Vision, whose only Use is to refract the Rays, as the known Experiment of a dark Room, with one only Hole to let in Light, through which a most exact Land-skip of every thing without, will be represented in its proper Colours, Heights and Distances, upon a Paper placed in the Focus of the Convex Glass in the Hole, which Experiment is to be found in almost every Book of Opticks, does plainly prove. Since the same thing will appear, if the crystalline Humour taken out of an Ox's or a Man's Eye, be placed in the Hole instead of the Glass. The Way how the watry Humour of the Eye, when by Accident lost, may be and is constantly supplied, was first found out and described by Monsieur Nuck (g)(g) De Ductibus novis Aquosis, who discovered a particular Canal of Water arising from the internal Carotidal Artery, which creeping along the Sclerotic Coat of the Eye, perforates the Cornea near the Pupil, and then branching its self curiously about the Iris, enters and supplies the watry Humour.(h) Galen de V. P. lib. X. c. II. As to the Vessels which moisten the Eye, that it may move freely in its Orbit, the Ancients knew in general that there were Two Glands in the Corners of the Eyes (h);(i) Observat. Anatomicæ de Oris Oculorum & Narium Vasis. but the Lympheducts, through which the Moisture is conveyed from those Glands were not fully traced till Steno (i) and Briggs (k) described them; so that there is just the same Difference between our Knowledge and the Ancients(k) Ophthalmographia. in this particular, as there is between his Knowledge who is sure there is some Road or other from this Place to that, and his who knows the whole Course, and all the Turnings of the Road, and can describe it on a Map.
The Instruments by which Sounds are conveyed from the Drum to the Auditory Nerves in the inner Cavities of the Ear, were very little, if at all, known to the Ancients. In the First Cavity there are Four small Bones, the Hammer, the Anvil, the Stirrup, and a small flattish Bone just in the Articulation of the Anvil and the Stirrup. It is now certainly known, that when the Drum is struck upon by the external Air, these little Bones, which are as big in an Infant as in adult Persons, move each other; the Drum moves the Hammer, That the Anvil, That the Stirrup, which opens the oval Entrance into the Second Cavity: None of these Bones were ever mentioned by the Ancients, who only talked of Windings and Turnings within the Os Petrosum, that were covered by the large Membrane of the Drum. Jacobus Carpus, one of the first Restorers of Anatomy in the last Age, found out the Hammer and the Anvil, Realdus Columbus discovered the Stirrup, and Franciscus Sylvius the little flattish Bone, by him called Os Orbiculare; but mistook its Position: He thought it had been placed Sideways of the Head of the Stirrup, whereas Monsieur du Verney (l)(l) Traité del' Organes de l'Ouye. Paris, 1683. finds that it lies in the Head of the Stirrup, between that and the Anvil. The other inner Cavities were not better understood, the spiral Bones of the Cochlea, that are divided into Two distinct Cavities, like Two pair of Winding-Stairs parallel to one another, which turn round the same Axis, with the Three semicircular Canals of the Labyrinthus, into which the inner Air enters, and strikes upon the small Twigs of the Auditory Nerves inserted into those small Bones, were things that they knew so little of that they had no Names for them; and indeed till Monsieur du Verney came, those Mazes were but negligently, at least unsuccessfully, examined by Moderns as well as Ancients; it being impossible so much as to form an Idea of what any former Anatomists asserted of the wonderful Mechanism of those little Bones, before he wrote, if we set aside Monsieur Perrault's (m)(m) Essays de Physique, Part II. Anatomy of those Parts, which came out a Year or two before; who is not near so exact as Monsieur du Verney.
The other Parts of the Head and Neck, wherein the Old Anatomy was the most defective, were the Tongue as to its internal Texture, and the Glands of the Mouth, Jaws and Throat. The Texture of the Tongue was but guessed at, which occasioned great Disputes concerning the Nature of its Substance, (n)(n) Vide Malpighium de Linguâ. some thinking it to be glandulous, some muscular, and some of a peculiar Nature, not to be matched in any other part of the Body. This therefore, Malpighius examined with his Glasses, and discovered, that it was cloathed with a double Membrane; that in the inner Membrane there are Abundance of small Papillæ, which have extremities of Nerves inserted into them, by which the Tongue discerns Tasts, and that under that Membrane it is of a muscular Nature consisting of numberless Heaps of Fibres which run all manner of Ways over one another like a Mat.
The general Uses of the Glands of the Mouth, Jaws and Neck were anciently known; it was visible that the Mouth was moistend by them, and the Mass of the Spittle supplied from them; and then, having named them from the Places near which they lie, as the Palate, the Jaws, the Tongue, the Ears, the Neck, they went no further; and there was little, if any thing, more done, till Dr. Wharton, and Nicolaus Steno examined these Glands. And upon an exact Enquiry Four several Salival Ducts have been discovered, which from several Glands discharge the Spittle into the Mouth. The First was described by Dr. Wharton (o)(o) Adenograph. cap. 21. near Forty Years ago: it comes from the conglomerate Glands that lie close to the inner side of the lower Jaw, and discharges it self near the middle of the Chin into the Mouth. The Second was found out by Steno (p) (p) Observat. Anat. de Oris Vasis.who published his Observations in 1662; this comes from those Glands that lie near the Ears, in the inside of the Cheek, and the outside of the upper-Jaw: The Third was found out (q)(q) Nuck Sialograp. by Thomas Bartholin, who gave an Account of it in 1682, and about the same Time by one Rivinus a German: It arises from the Glands under the Tongue, and going in a distinct Canal to the Mouth of Wharton's Duct, there, for the most Part, by a common Orifice, opens into the Mouth. The Fourth was discovered by (r) Ibid.Monsieur Nuck (r); he found a Gland within the Orbit of the Eye, from which, not far from the Mouth of Steno's Duct, Spittle is supplied to the Mouth by a peculiar Canal. Besides these, the same Monsieur Nuck found some smaller Glands near the last, but lower down, which by Four distinct Pipes carry some Spittle into the Mouth; so careful has Nature been to provide so many Passages for that necessary and noble Juice, that if some should fail, others might supply their Want.