8. The Reformatory Period.

[Comprehending the 17th and the 18th Centuries.]

"We have just seen the systems of Aristotle and Galen resist the premature attacks of the partisans of the Occult Sciences, and enlist the majority of intellects, save some partial modifications impressed upon them by less bold and more sensible innovators. The long duration of these systems, the almost unanimous agreement of the great men of antiquity and of the middle ages in their favour, formed them into the most respectable of precedents, which as yet was disdained but by few. It is no-wise astonishing, then, that the most eminent men of science should prefer them to the crotchetty and ill-elaborated theories of the contrivers of the occult doctrines-those restless, capricious, and haughty spirits who attempted to arrogate to themselves the sceptre of knowledge, without having taken any pains to ripen a plan of scientific reform, whose wisdom and grandeur might justify so high a pretension in the eyes of enlightened men.

"Nevertheless, the domain of the natural sciences became enlarged from day to day. During the two last centuries, observation had enriched it with a multitude of new facts which ill squared, or squared not at all, with accredited doctrines; and the time approached when the necessity of a radical reform was felt in almost every branch of human knowledge. Men, whose learning equalled their genius, are about to appear to direct this intellectual movement, and to substitute, for the decrepid theories of the schools, newer and more powerful ones, better harmonizing with the range of ascertained phenomena. To the worship of the ancients is about to succeed an immoderate desire of shaking the yoke of their authority, to, as it were, avenge their prolonged tyranny. This is why I have termed the period Reformatory-a term which, if I mistake not, perfectly characterizes the general tendency of mind, the predominant idea, and the prominent fact of the epoch."-Tom. II. p. 156.

At the commencement of this period Galileo opened the way for the regeneration of physical science, and following the rigid spirit of observation, in place of the fashionable subtleties of the day, he became the parent of several discoveries, any one of which would have served to immortalize him. "The bold and happy hypotheses of Kepler also opened up the way of the heavens to Newton." Naturalists now freely availed themselves of the aid afforded by the miscroscope; while a new race of chemists, abandoning the dreams of alchemy, and adopting experiment as their guiding star, were among the most potent adversaries of the old philosophy, Theories in medicine were now no longer received on account of the ingenuity of their conception, and not only did Galenism, but several new systems as well, receive their death-blow; for, "although these last had been devised and sustained by men of superior merit, they all erred in considering the phenomena of the animal economy only under some of its points of view, neglecting others just as important. All, too, erred in the no less grave error of exceeding in their abstractions the limits of sensible phenomena. This is why they all vanished, or became entirely modified, after enjoying a more or less ephemeral reputation."

M. Renouard, as in the former periods of this history, but at much greater length, reviews the state of medical science at this epoch, casting a retrospective glance from time to time at the steps by which it has arrived at so improved a condition. We can only sparingly follow him, as we are desirous of alluding, also, to the various novel theories which so remarkably characterized this period of intellectual activity and learned research.

1847.]

The Reformatory Period.

1. Anatomy and Physiology.

411

The anatomists of the 16th century had so accurately described all the most obvious parts of the frame, that little remained for their successors to accomplish in this respect; but, directing their attention to minute and comparative anatomy and to experimental physiology, they reaped some most excellent discoveries.

The Circulation. According to the ancient doctrines, the liver was the organ of sanguification, and there the veins, they being the only vessels which contained blood, took their origin. The blood was supposed to be sent to and return from all parts in these same canals, by a sort of undulatory movement. The arteries were stated to contain the vital spirits, whose great reservoir was the heart. Galen modified this doctrine by showing that the arteries likewise contained blood. He was aware, too, that this fluid was brought by the large veins into the right cavities of the heart; but he maintained that, while a small portion passed to the lungs by the pulmonary artery, the great mass penetrated the pores of the septum into the left ventricle. This opinion was uncontested until the time of Servetus in the 16th century, who denied the passage of the blood through the septum, and maintained that it passed through the lungs by the pulmonary artery, and was returned to the left ventricle by the pulmonary veins. Columbus soon after proved this to be correct by anatomy, and explained the true use of the cardiac valves. Casalpinus added that the minute arterial ramifications communicated with the veins in the lungs. The existence of valves in the veins was already known; so that it seemed to require, at the commencement of the 17th century, but one step for the discovery of the circulation-a difficult one however. Harvey attended the lectures of the celebrated Fabricius de Aquapendente at Padua during four years. The venous and cardiac valves were demonstrated by the unconscious professor to his young pupil, thus casting a germ into his fertile mind which years after was to spring up and flourish into the goodliest tree of science. His first announcement of his discovery was in his lectures at the College of Physicians in 1615; but not until 1628 did he consider his observations sufficiently mature for publication. "England," says Haller, "had contributed nothing to anatomical science, when, behold, a man appears, whose discoveries constitute the only grand epoch in its history since the days of Hippocrates." M. Renouard does justice to the admirable course which Harvey adopted, both in pursuing and confirming his investigations, and in meeting the vehement opposition he triumphantly contended with. We are loath to mar so important a theme by a mere incidental allusion; but certain we are that no greater service can be done our profession, and especially the younger members of it, than the taking some more fitting opportunity for exhibiting in detail the lessons deducible from the example of this truly great man.

"This theory, which now appears to us so natural," says M. Renouard, "that we can hardly understand why it was not discovered long before, was however nothing less than a revolution in physiology." Truly so; and we may compendiously say, that a principal occupation of subsequent physiologists and physicians has been to multiply proofs of the truth of the doctrine, explain the mechanism of the various structures concerned,

and direct its practical applications to the prevention or removal of disease and the relief of accidents. Malpighi, with the aid of the microscope, demonstrated the actual progress of the globules in the small vessels; and Leuwenhoek traced the same, before numerous witnesses, into the minutest ramifications. In 1749, Senac published his great work on the Heart, and its Diseases, which excited so much the admiration of his cotemporaries, and especially of Morgagni. His ideas upon the cause of the movements of the heart were fanciful in the extreme; but the diagnosis of its diseases received all the perfection it was capable of, prior to the discovery of auscultation and percussion.

2. Respiration.-Prior to the 17th century, it was believed that the air which penetrated into the bronchial ramifications was in part subtilized and conveyed by the pulmonary veins to the heart for the fabrication of the vital spirits, and in part exhaled with the fuliginous matters of that organ during expiration. In this way the lungs were cooled and freed from tho danger of their proximity to the heart, the centre of animal heat, and an æther or pneuma provided as a source of the vital spirits. The discovery of the circulation destroyed the basis of this theory: and in 1661, Malpighi demonstrated the cellular structure of the lungs. Borelli, Helvetius, Haller, and others, made numerous experiments upon the manner in which the inspiratory and expiratory movements of the chest are effected, and established the facts as they are now received. Various pneumatic theories were invented, but were unable to hold their ground after the discovery of the changes which the air underwent during respiration. Mayow's experiments in 1668 opened the way for future observers, and Lavoisier, towards the end of the 18th century, presented us with his chemical theory, so seductive by its simplicity. With this of course our readers are familiar, as with the objection derivable from the influence of the nervous system not having been taken into account. M. Renouard takes no notice of Dr. Adair Crawford's important Essay, so confirmatory of Lavoisier's views.

3. Lymphatic System.-Herophilus and Erasistratus had seen white vessels in the mesentery of some animals, and mistook them for arteries full of air. Galen, who never saw them, regarded the observation as chimerical, and taught that the veins of the mesentery absorbed the chyle from the intestines, and carried it to the liver, where it was transformed into blood; and his opinion was dominant until the middle of the 17th century. Eustachius had, in 1563, described the thoracic duct in the horse, without however suspecting its use. In 1622, Gaspard Aselli, dissecting a dog who had been killed shortly after feeding, observed several white filaments in the mesentery, which he mistook for nerves. Having accidentally pricked he was astonished to see a creamy fluid flow out; and a repetition of the examination in other dogs enabled him to establish the existence of the lacteals, as also of their valves. He believed they all went to the pancreas, and thence to the liver, which was then the acknowledged organ of sanguification. In 1647, Pecquet, while yet a student, discovered the thoracic duct. He also showed that the lacteals did not go to the liver, but emptied themselves into this reservoir-thereby inflicting the final blow

one,

1847.]

Progress of Anatomy and Physiology.

413

upon the doctrine which for ages had declared the liver the organ of hæmatosis. The investigation of the lymphatic glands and vessels henceforth occupied the attention of a great number of celebrated anatomists, as Vesling (who indeed discovered the thoracic duct about the same time as Pecquet), Bartholin, Ruysch, Rudbeck, the Hunters, Hewson, Cruickshank, and Mascagni, who published (1787) the first plates of the entire lymphatic system.

4. The Nervous System.-Hippocrates and his successors in the School of Cos possessed no precise idea of the functions of the nervous system, confounding, under the name of nerves, ligaments, tendons, and the nerves themselves; and it would seem that to Herophilus, the famous professor of the School of Alexandria, is due the earliest correct notions upon the subject. He describes three sorts of nerves; the first, which serves for the sensations and voluntary movements springing from the brain and spinal marrow; the second and third being destined to unite the bones together, and these to the muscles. Herophilus thus had not entirely thrown off the old error of confounding nerves and tendinous structure, and Galen was not exempt from similar views. He describes the brain and its membranes with accuracy, stating his belief that the cerebrum is the seat of the mind, and the origin of the nerves of sensation, while the cerebellum and spinal marrow give rise to those of voluntary motion. He maintains, however, that the extremities of the nerves are expanded into ligaments, membranes, and tendons; and places the sense of touch in the membranes covering the muscles, which have indeed, from their supposed origin in the nervous substance, received their name of aponeuroses. The anatomists of the 16th century described the distribution of the vessels and nerves with more accuracy; but most of the ancient errors on sensation and motion continued to prevail; and even in the 17th century Baglivi derived all vital movements from the heart and dura mater. The researches of Vieussens, Haller, Meckel, Vicq. d'Azyr, Soemmering, &c., during the last century, however, sufficiently demonstrated the true functions and structure of the organ. The opinions which attributed important functions to the dura mater, and the derivation of membranes from nervous ramifications, were proved to be destitute of foundation. It was shown that the medullary pulp of the nerves of the senses receiving the impressions transmitted them to the brain. The ancients had been more complex in their contrivances, and believed, as taught by Empedocles, that an elementary affinity prevailed between external objects and the organs of the senses-each organ possessing its element capable of attracting similar molecules of external bodies. The eye, for example, being of a resplendent nature, attracts the luminous molecules of bodies; the ear of an airy nature, those which are sonorous, &c Galen only added to the hypothesis the doctrine of spirits which were secreted by the brain, and transmitted to the organs of sense, visual spirits to the eye, where they entered into contact with the luminous particles of bodies, &c. Such were the ideas which prevailed even to the 17th century. At that period Kepler showed the crystalline lens was not, as believed until then, the organ of vision, but an instrument for refracting the image of objects upon the retina; and Scheiner demonstrated this expansion to be the No. 108

27

true organ of sight. The researches of Newton on light and colours much contributed to the establishment of a true theory of vision.

Bonet

The functions of the nervous system have much occupied the attention of the moderns. Some have regarded the nerves as delicate tubes containing a subtle fluid, which, receiving the impressions of objects, transmits them to some central point of the encephalon. Others look upon the nervous fibrils as cords springing from a common centre. revived the hypothesis of Hartley, which supposes every nerve to contain as many distinct fibres as it receives different sensations. Thomas Willis first assigned special functions to various portions of the brain, as common sense to the corpora striata, memory to the cortical substance, &c. Cabanis likened the functions of the organ to those of other viscera, it producing all the operations of the intellect, just as the stomach and intestines accomplish the digestion of food or the liver secretes bile. All these were mere hypotheses; but others founded their opinions upon servation, as Camper, in that which he estimates the mental development by the facial angle. Pinel, from his observations upon the insane, came to the conclusion, that the various faculties of the brain must have a special affection to a special portion of that organ; and it was at the end of this period that Gall commenced announcing the results of his prolonged investigations.

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5. Generative System.-Galen described the male apparatus with accuracy, and recognised the analogy of the organs of the two sexes-the male organs being developed externally by the heat of the temperament, while those of the female were retained within by reason of her natural coldness. He called the ovaries the female testicles, and believed they secreted a fluid during copulation analogous to the semen of the male. Dissecting only animals, he believed the uterus was divided into two cavities. The male and female semen becoming mixed in the womb, the latter serves for the nourishment of the other, and for the production of one of the fœtal membranes. The male semen is almost at once converted into membranes, some of which afterwards become expanded and hardened, and modulated into the various parts of the foetal frame. With Hippocrates, Galen believed the right testis furnished the material for male ova, the left for female, the female embryo always becoming developed in the left, and the male one in the right cavity of the uterus. These views remained entirely unchanged until the 16th century. Even then the chief anatomical errors of Galen only were rectified; and it required the successive investigations of Fabricius, Harvey, and De Graaf to bring our knowledge of the true structure of these organs to its present state. As to the theories of generation, which may all be reduced to the two principal hypotheses of epigenesis and evolution, M. Renouard observes that, after the endless disputations it has led to, the question is as undecided as ever.

6. The Vital or Organic Properties.-Philosophers and physiologists of all periods have agreed in recognising under the term essence, nature, soul, spirit, pneuma, &c., the existence of a primary intrinsic power presiding over the various functions of the body as well as that of the physical and