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disease and injury, it is evident that he is justly entitled to be regarded as the father of pathological surgery, and as the first who raised surgery from the rank of an art to that of a science. If this had been all he ever did, what name in the annals of medicine could have had a prouder claim to distinction ?
The first approach to an accurate knowledge of the anatomy of the lymphatic system, and the establishment of its true functions, are due to the conjoint labours of William and John Hunter. The existence of lymphatic vessels had long been known; and, somewhat earlier than the time of the Hunters, conjectures had been thrown out as to their absorbent action; but their relation to the lymphatic glands, and their connexion in one entire system permeating the whole animal frame, and ministering to an important general function, were brought to light for the first time by the researches of these distinguished brothers.*
John Hunter showed that an injection of mercury, forced into the substance of the lymphatic glands, would fill not only the glands, but all the lymphatic vessels proceeding from them; and it was his intention to have traced the lymphatics in this manner throughout the body, and to have given a complete description and figure of the whole absorbent system; but he was prevented, by a long illness, from prosecuting his design. His brother William bears witness to these facts, and Cruikshank, who perfected the anatomy of the absorbent system, distinctly acknowledges the priority of John Hunter. An immediate application of the physiological views developed by his own and his brother's researches was made by John Hunter in his beautiful theory of the action of the lymphatics in balancing that of the nutritive vessels, and modelling the different organs of the body into their just shape and proportions. Still more important was the use which he made of these discoveries in explaining the process of ulceration, which constitutes "perhaps one of the most successful efforts that has hitherto been made by any pathologist to apply the knowledge of a living function to the explanation of morbid appearances."+
Among the general subjects on which Hunter exercised his versatile powers was the venereal disease. In the investigation of this, however, he fell far short of the excellence which he attained on most other subjects involving the illustration of general principles, and the application of vital laws to the elucidation of morbid actions. Still, he was undoubtedly the first who cultivated this subject in a scientific spirit; and there is one point of view in which his treatise may be considered as particularly valuable-namely, as the earliest attempt to illustrate the laws of morbid poisons. Many of Hunter's theoretical views of syphilis have been proved, by more recent observation, to be erroneous, such as that of its invariable tendency to go on from bad to worse, and that of its incurability by any other than a specific remedy.
It must be confessed, however, that they fell into a great error in denying the absorbent power of the veins, which was then generally admitted; and that they thus made a step backward, as well as one in advance.
t Thomson's Lectures on Inflammation, p. 369.
But Hunter did not excel in pure theory; his mind was not of a logical cast; and his hypothetical reasoning was often-nay, almost alwaysvague and inconclusive. His forte lay in seizing with amazing sagacity on those points of a subject which afforded scope for anatomical demonstration, or physiological experiment-in bringing to bear on such points a most exact and comprehensive knowledge of comparative structure and in devising, with the most subtle ingenuity, experiments directly adapted to solve the point at issue. The venereal disease was not a subject which afforded much scope for these qualities, and therefore, as truly remarked by Dr. George G. Babington in his preface to the treatise, it "was less adapted than many other subjects to the peculiar genius of John Hunter." It is not to be denied, however, that Hunter brought to the illustration of the venereal disease the same laborious observation of facts which characterizes all his works. His delineation of its local and constitutional effects is given with a masterly hand, and his precepts for its treatment have in the main held their ground amid all subsequent fluctuations of opinion. Before he took the subject in hand it was quite out of the pale of scientific inquiry, and the treatment of the disease was altogether empirical and unsatisfactory. He left it enriched with copious and correct observations, and with sound views of treatment; so that his treatise on this subject, though it will not bear a comparison with his greater works, is still of no ordinary merit, and must be regarded as the production of a very great pathological and practical surgeon.
The observations of Hunter on the nervous system were perhaps less extensive than might have been expected from so ingenious and indefatigable an inquirer. This seems to have been one of the few instances in which speculative views occupied him too much, to the exclusion of that inductive method of research which usually guided him to such sound and beneficial results. On some points, however, following his accustomed modes of inquiry, he arrived at highly important conclusions. He distinctly showed that organs which are endowed by one nerve with a special sense, derive their common sensation from another nerve having a different origin; and he determined this nerve of common sensation, in the case of the eye, the nose, and the ear, to be the nerve of the fifth pair. He extended the same reasoning to the organ of taste, though he did not verify it, as in the preceding instances, by anatomical demonstration. Hunter, therefore, unquestionably originated, and pursued with no trifling success, that method of inquiry into the functions of the nervous system which Sir C. Bell afterwards carried out to so large an extent, and with such brilliant results. Another observation of great interest, both in a physiological and psychological point of view, was first made by Hunter-namely, that nerves adapted to the reception of peculiar impressions convey such peculiar impressions to the brain, though merely a mechanical stimulus be applied to them; and he instances the sensation of light produced by a mechanical impression on the retina, and that of sound by a similar impression on the acoustic nerve. Later experiments have extended this observation, by showing that if
the stimulus be of a chemical or electrical, instead of a mechanical nature, the nerve will still convey its appropriate impression.
There is no function which Hunter has more largely illustrated by an appeal to comparative structure, than that of digestion, and the preparations in his museum displaying the anatomy of the organs which minister to this function, from the lowest animals up to man, form a most beautiful and truly instructive series. The power of living matter to resist the action of the gastric fluid had already been incidentally remarked by Grew; but Hunter adduced a most interesting illustration of the fact, in the case of the stomach itself, by showing that in some instances this organ is partially dissolved after death by the very fluid which it secreted while living. This fact has been disputed, and the phenomena referred to morbid actions going on during life by Cruveilhier and others; but the experiments of Dr. Carswell have set the matter at rest, and established the correctness of Hunter's views.
That the act of vomiting is performed by the diaphragm and abdominal muscles, while the stomach itself is passive, was a position maintained by Hunter, though M. Magendie imagined that he was the first to discover the fact.
To John Hunter we unquestionably owe the resuscitation of the study of transcendental or philosophical anatomy. This study did, in truth, originate with Aristotle; but that extraordinary man was, in this respect, not years only but two thousand years in advance of the age in which he lived; and neither Hunter, nor others far more learned than he, had any conception of the physiological treasures sealed up in the writings of the "mighty Stagyrite"-treasures which have fully come to light only within the last thirty years.
In Hunter's descriptions of his drawings illustrative of the development of the chick, is the following very remarkable passage:
"If we were capable of following the progress of increase of the number of parts of the most perfect animal, as they first formed themselves in succession from the very first, to its state of full perfection, we should probably be able to compare it with some one of the incomplete animals themselves, of every order of animals in the creation, being at no stage different from some of those inferior orders; or, in other words, if we were to take a series of animals from the more imperfect to the perfect, we should probably find an imperfect animal corresponding with some stage of the perfect."
Surely never was an original and magnificent conception so poorly clad in language! But here is the unequivocal announcement of a theory which, though too absolutely adopted by some writers, has exercised, and is worthy to exercise, no small influence on the reasonings of philosophical anatomists.
The subject of monstrosities engaged much of Hunter's attention. He framed a classification of them, and produced them artificially by curious and well devised experiments on living animals. He arrived at the conclusion that such deviations from ordinary structure were not, as it was then the fashion to term them, lusus naturæ; for he observed that every species had a disposition to deviate from normal
development in a manner peculiar to itself-a position virtually the same with that which M. Isidore St.-Hilaire makes the basis of his celebrated treatise on the Anomalies of Organization.' Hunter explained congenital defects by a reference to the transitory structures of intra-uterine life. It was thus that he solved the question how the intestine came to be in contact with the testicle in congenital hernia. He observed the position and relations of the gland in the abdomen of the foetus; traced its descent into the scrotum; found that it carried along with it a peritoneal pouch like a hernial sac; and showed that, in the event of the simultaneous passage of a portion of intestine, this pouch must remain a common receptacle for the intestine and the testis. He then went on to show how the abdominal position of the testis, and the transitory condition of the tunica vaginalis in the human fetus, are permanent conditions in the lower mammalia.
Of Hunter's labours in the field of zoology it is now impossible to form a complete estimate, because that portion of his manuscripts in which his observations in this department were especially recorded, was destroyed by Sir Everard Home. Sufficient however remains, collected in his museum, and scattered through his published writings, to prove how great must have been the entire amount of his contributions.
He made several attempts at a classification of animals based on their anatomical structure. One of these he derived from the distribution of the nervous system; another from the reproductive organs; and another from the structure of the heart. The first was not carried out to its full extent; the second was relinquished as unsatisfactory; and the third was only an improvement upon that of Linnæus. Hunter, however, made very important advances towards a perfect classification of animals according to the distribution of the nervous system; and there was a stage of his inquiries at which, if he had not been deserted by his usual acuteness, he would assuredly not have left for Cuvier the grand division of animals into vertebrata and invertebrata. Hunter notes the aggregation of the nervous system into spinal and cerebral masses, as distinguishing fishes from those animals which are now called mollusca and articulata; but he did not perceive that the existence of this cerebro-spinal axis is equally characteristic of the classes above fishes; neither did it occur to him that, wherever there is a cerebro-spinal axis, there is also a bony case for it. The study of what is now styled paleontology was in its infancy in Hunter's days. But there is a paper of his on some fossil bones, presented to the Royal Society by the Margrave of Anspach, which shows that he had much larger and more enlightened views on the subject than any which were then generally entertained. Professor Owen has given an analysis of his paper, which we here transcribe, as being more to the purpose than anything which we could offer.
"In this paper, we may perceive that Hunter appreciated the value of the study of fossil remains, and their application to the elucidation of many important objects. First, with reference to the extension of our ideas respecting the zoology of this planet, we find him comparing the fossils which are the
subject of the text with their recent analogues, and he shows that they differ both from them, and among themselves: his observations and comparisons are, it is true, too general and summary, and it was left to his successors in this field of inquiry to pursue the comparison with the requisite minuteness and precision, and to give names to the distinct but extinct species. Hunter next briefly alludes to the different situations and climates in the globe to which animals are more or less confined; and this subject, or the geographical distribution of animals considered in relation to fossil remains, elucidates, amongst other interesting questions, the changes of temperature to which different parts of the earth have been subject at different epochs. Hunter points out more distinctly, and with more detail, the evidence which extraneous fossils afford respecting the alternations of land and sea of which the earth's surface has been the theatre; and by his frequent allusion to the many thousand years which must have elapsed during these periods, seems to have fully appreciated the necessity of an ample allowance of past time in order to account philosophically for the changes in question. Lastly, he treats of the nature and causes of the different states in which the remains of extinct animals are found: and many of the fossil bones which are the subject of his chemical experiments are still preserved in his muscum.'
Having thus taken a cursory view of Hunter's doctrines and opinions, and of the general principles which he sought to establish, we proceed to notice some of the more remarkable of his particular discoveries, and these we shall take in the order in which they suggest themselves, 1. He discovered and described the organ of hearing in the sepiaa discovery which has been attributed by Cuvier to Scarpa.
2. He first described the semicircular canals in the cetacea, the observation of which Cuvier claims for himself.
3. He preceded Camper by a short time in the discovery of the aircells in the bones of birds, though there is no reason to doubt the originality of Camper in the same observation.
4. He discovered the peritoneal canals, or openings, in the eel, salmon, and cartilaginous fishes, as also in the crocodile.
5. He described the continuation of the peritoneal canals into the corpus cavernosum penis in the chelonia - an observation brought forward as new by M. Isidore St.-Hilaire and Martin St. Ange.
6. He discovered the motion of the blood in insects, describing correctly the action of the dorsal vessel, and the relation of the circulatory to the respiratory systems-points on which Cuvier was subsequently in error.
7. He first observed the bi-auricular structure of the heart in the caduci-branchiate batrachia.
8. He discovered that the tubuli uriniferi extend to the surface of the kidney.
9. He first described the renal organ in the snail.
10. He discovered the circular arrangement of the nervous ganglia round the oral aperture of the mollusca, as also the double abdominal nervous cord of the articulata.
11. Conjointly with his brother William, he ascertained the true nature of the connexion between the placenta and the uterus. How much of the merit of this was due to each, it is impossible to deterNote to Hunter on the Animal Economy, pp. 479, 480.