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One of the ablest of his commentators has justly observed, that his natural inclination was, to conjecture what the laws of nature were, and then reason from them, instead of reasoning to them by slow and gradual induction.240 This process of deduction was, as I have shown, the favourite method of all Scotchmen, and, therefore, was precisely the course which we should have expected him to adopt. But, inasmuch as he was surrounded by the followers of Bacon,241 this natural bias was warped, and a large part of his marvellous activity was employed in observations and experiments, such as no Scotch thinker, living in Scotland, would ever have engaged in. He himself declared, that thinking was his delight; 242 and there can be no doubt that, had he been differently situated, thinking would have been his principal pursuit. As it was, the industry with which he collected facts, is one of the most conspicuous features in his career. His researches covered the whole range of the animal kingdom, and were conducted with such untiring zeal, that he dissected upwards of five hundred different species,

240" He followed his natural inclination. He preferred the more delusive, apparently the more direct, road, which has seduced so many philosophers. He sought to arrive at the general laws of nature at once by conjecture; rather than, by a close and detailed study of her inferior operations, to ascend, step by step, through a slow and gradual induction to those laws which govern her general procedure.' Babington's Preface to Hunter's Treatise on the Venereal Disease, in Hunter's Works, vol. ii. p. 129. Compare the narrow and carping criticism in Foot's Life of Hunter, p. 163.

241 That I may not be suspected of exaggeration, I will quote what by far the greatest of all the historians of medicine has said upon this subject. "La majorité des médecins qui prétendaient s'être formés d'après Bacon, n'avaient hérité de lui qu'une répugnance invincible pour les hypothèses et les systèmes, une grande vénération pour l'expérience, et un désir extrême de multiplier le nombre des observations. Ce fut chez les Anglais que la méthode empirique en médecine trouva le plus de partisans, et c'est principalement aussi chez eux qu'elle s'est répandue jusqu'aux temps les plus rapprochés de nous. Sa propagation y fut favorisée, non-seulement par le profond respect que les Anglais continuent toujours de porter à l'immortel chancelier, mais encore par la haute importance que la nation entière attache au sens commun, common sense, et elle y demeura l'ennemie irréconciliable de tous les systèmes qui ne reposent pas sur l'observation." Sprengel, Histoire de la Médecine, vol. v. p. 411, Paris, 1815.

242 Clive says,

He

"Much as Mr. Hunter did, he thought still more. has often told me, his delight was, to think." Abernethy's Hunterian Oration, London, 1819, p. 26.

exclusive of dissections of different individuals, and exclusive, too, of dissections of a large number of plants.243 The results were carefully arranged and stored up in that noble collection which he formed, and of the magnitude of which we may gain some idea from the statement, that, at his death, it contained upwards of ten thousand preparations illustrative of the phenomena of nature.244 By this means, he became so intimately acquainted with the animal kingdom, that he made a vast number of discoveries, which, considered singly, are curious, but which, when put together, constitute an invaluable body of new truths. Of these, the most important are, the true nature of the circulation in crustacea and insects; 245 the organ of hearing in cephalopods; 246 the power possessed by mollusks of absorbing

243 Mr. Owen, in his interesting Preface to the fourth volume of Hunter's Works, says (p. vii), "There is proof that Hunter anatomized at least five hundred different species of animals, exclusive of repeated dissections of different individuals of the same species, besides the dissections of plants to a considerable amount."

241 "Some idea may be formed of Hunter's extraordinary diligence, by the fact, that his museum contained at the time of his death, upwards of 10,000 preparations, illustrative of human and comparative anatomy, physiology, and pathology, and natural history." Weld's History of the Royal Society, London, 1848, vol. ii. p. 92.

245

"I have tested the conflicting evidence of these observers by dissection of the heart in the lobster; and you will perceive by this preparation that it is more complicated than even the Danish naturalist supposed, and fully bears out the opinion of Hunter in regard to the mixed nature of the circulation in the crustacea." Owen's Lectures on the Comparative Anatomy and Physiology of the Invertebrate Animals, 2d edit. London, 1855, p. 318. "Cuvier, misled by the anomalous diffused condition of the venous system, supposed that there was no circulation of the blood in insects; yet the dorsal vessel was too conspicuous a structure to be overlooked. Such, however, was the authority of the great anatomist, that the nature of the heart began to be doubted, and the strangest functions to be attributed to it. Hunter, however, who was prepared to appreciate the true state of the circulating system in insects, by his discovery of the approximately diffused and irregular structure of the veins in the crustacea, has described, in his work on the blood, all the leading characters of the circulation in insects as it is recognized by comparative physiologists of the present day." Ibid., p. 383. Compare Hunter's Essays and Observations on Natural History, London, 1861, vol. i. p. 108.

248 The class called Sepia has the organ of hearing, though somewhat differently constructed from what it is in fishes." An Account of the Organ of Hearing in Fishes, in Hunter's Works, vol. iv. p. 294. At the bottom of the page Mr. Owen observes, in a note, "This is the first announcement of the existence of an organ of hearing in the Cephalopoda.'

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their shells; 247 the fact that bees do not collect wax, but secrete it;248 the semicircular canals of the cetacea; 249 the lymphatics of birds; 250 and the air-cells in the bones of birds, 251 We are also assured, that he anticipated the recent discoveries respecting the embryo of the kangaroo; 252 and his published works prove, that, in the human subject, he discovered the muscularity of the arteries,253 the muscularity of the iris,254 and the diges

247 Hunter discovered that the molluscous inhabitant of a shell had the power of absorbing part of its dwelling." Owen's Lectures on the Comparative Anatomy and Physiology of the Invertebrate Animals, London, 1855, p. 544. "Every shell-fish has the power of removing a part of its shell, so as to adapt the new and the old together, which is not done by any mechanical power, but by absorption." Anatomical Remarks on a New Marine Animal, in Hunter's Works, vol. iv. p. 469, edit. Palmer. In a note to this passage, it is said, that "the doctrine of the absorption of shell has been lately" (i. e. in 1833) "adduced as a new discovery."

248 His keen observation did not fail to detect several errors which preceding naturalists had fallen into, especially with regard to the formation of the wax, which he proved to be secreted, not collected, by the animal.” Ottley's Life of Hunter, p. 122. "The wax is formed by the bees themselves; it may be called an external secretion of oil, and I have found that it is formed between each scale of the under side of the belly." Observations on Bees, in Hunter's Works, vol. iv. p. 433.

249"In the terminating part there are a number of perforations into the cochlea, and one into the semicircular canals, which afford a passage to the different divisions of the auditory nerve." Observations on the Structure and Economy of Whales, in Hunter's Works, vol. iv. pp. 383, 384. "The semicircular canals of the cetacea, described by Hunter in the paper on Whales, a structure which Cuvier rightly states that Camper overlooked, but incorrectly claims the discovery as his own." Preface to vol. iv. of Hunter's Works, p. xxi.

250 Dr. Adams, in his somewhat hasty Life of Hunter, says (pp. 27, 28), "Mr. Hewson always claimed the discovery of lymphatics in birds." But the truth is, that Hewson never claimed it. He says, "It may be necessary to mention here, that the dispute between Dr. Mouro and me is, who first discovered the lacteals of birds? for as to the lymphatics in their necks (mentioned in this gentleman's note), these we both allow were discovered by Mr. John Hunter, about ten years ago." And, again, "These lymphatics in the necks of fowls were first discovered by Mr. John Hunter." Hewson's Works, edit. Gulliver (Sydenham Soc.), pp. 102, 145.

251 Hunter's Works, vol. iv. pp. xxi. 176.

252 See Nos. 3731, 3734, 3735, in the Physiological series of the Hunterian Museum, in which there are evidences that Mr. Hunter had anticipated most of the anatomical discoveries which have subsequently been made upon the embryo of the Kangaroo.' Rymer Jones' Organization of

the Animal Kingdom, London, 1855, pp. 829, 830.

253 The muscularity of arteries, of which John Hunter made physiological proof, is now a matter of eyesight." Simon's Pathology, London, 1850, p. 69. "To prove the muscularity of an artery, it is only necessary [254 For this Note, see next page.]

tion of the stomach after death by its own juice.255 Although, in his time, animal chemistry was not yet raised to a system, and was consequently little heeded by physiologists, Hunter endeavoured, by its aid, to search out the qualities of the blood, so as to ascertain the properties of its constituents.256 He also examined it in different stages of embryonic life, and by minutely tracking it through its periods of development, he made the capital discovery, that the red globules of the blood are formed later than its other components. His contemporaries, however, were so little alive to the importance of this great physiological truth, that it fell dead upon them, and, being forgotten, it was, about fifty years afterwards, rediscovered, and was announced, in 1832, as a law of nature which had just been brought to light.25

"When

to compare its action with that of elastic substances." the various uses of arteries are considered, such as their forming different parts of the body out of the blood, their performing the different secretions, their allowing at one time the blood to pass readily into the smaller branches, as in blushing, and at another preventing it altogether, as in paleness from fear and if to these we add the power of producing a diseased increase of any or every part of the body, we cannot but conclude that they are possessed of muscular powers." Hunter's Works, vol. iii. p. 157. See also vol. iv. p. 254. Mr. Gulliver, in his edition of Hewson's Works, London, 1846, says (p. 125), that Hunter's "experiments on the functions of the arteries are supported by the latest and best observations on their structure."

254The fact of the muscularity of the iris, which is here presumed from analogy by Mr. Hunter, has been since directly proved by the observations of Bauer and Jacob (Phil. Trans. 1822), and indirectly by Berzelius, who found that the iris possesses all the chemical properties of muscle." Palmer's note in Hunter's Works, vol. iii. p. 146, London, 1837.

255 Adams' Life of Hunter, pp. 59, 60, 245. Hunter's Works, vol. i. p. 43; vol. iv. pp. 116-121. Watson's Principles of Physic, vol. ii. p. 440.

But

256 Hunter subjects the blood to both mechanical and chemical analysis, and endeavours to determine the characteristic properties of its different constituents." Owen's Preface to vol. iv. of Hunter's Works, p. xii. this gives, perhaps, rather too high an idea of his animal chemistry; for such was then the miserable state of this extremely important branch of knowledge, that he arrived at the conclusion that "blood gives no analysis excepting that of common animal matter." Principles of Surgery, chap. iii. in Hunter's Works, vol. i. p. 229.

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257 In seeking to determine the respective importance of the different constituents of the blood, by the philosophical and most difficult inquiry into their respective periods of formation in the development of the embryo, Hunter made the interesting discovery that the vessels of the embryo of a red-blooded animal circulated in the first instance colourless blood, as in the invertebrate animals. The red globules,' he observes, 'seemed to be formed later in life than the other two constituents, for we see while the

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This is one of many instances in the history of our knowledge, which proves how useless it is for a man to advance too far beyond the age in which he lives.258 But Hunter, besides making the discovery, also saw its meaning. From it, he inferred, that the function of the red globules is to minister to the strength of the system, rather than to its repair.259 This is now universally admitted; but it was not admitted till long after his death. Its recognition is chiefly owing to the rapid advance of animal chemistry, and to improvements in the microscope. For, by the employment of these resources, it has become manifest, that the red globules, the respiratory process, the production of animal heat, and the energy of the locomotive organs, are but different

chick is in the egg the heart beating, and it then contains a transparent fluid before any red globules are formed, which fluid we may suppose to be the serum and the lymph.' I well remember the feelings of surprise with which I listened, while at Paris in 1832, to a memoir read before the Academy of Science, by MM. Delpech and Coste, the object of which was the announcement of the same fact as a novel and important discovery. The statement of the French observers was received with all the consideration which its importance justly merited, without its being suspected that our great physiologist had, half a century before, embraced it, with all its legitimate deductions, in the extended circle of his investigations." Owen's Preface to vol. iv. of Hunter's Works, p. xiii.

258 Indeed, if we may rely on the references recently given by Mr. Gulliver, which, from his great general accuracy, there seems no reason to question, the fact that the pale blood precedes the red, was known even in the time of Glisson. See Gulliver's learned edition of Hewson's Works, London, 1846, p. 222. But, to the contemporaries of Glisson, such a fact was isolated, and consequently useless. Nothing is valuable while it appears to stand alone.

259From the above account it appears that whatever may be their utility in the machine, the red globules certainly are not of such universal use as the coagulating lymph, since they are not to be found in all animals, nor so early in those that have them; nor are they pushed into the extreme arteries, where we must suppose the coagulating lymph reaches; neither do they appear to be so readily formed. This being the case, we must conclude them not to be the important part of the blood in contributing to growth, repair, &c. Their use would seem to be connected with strength." A Treatise on the Blood, Inflammation, and Gun-shot Wounds, in Hunters Works, vol. iii. p. 68. In another remarkable passage, he touches on the possibility of an increase in the amount of red globules being connected with an increase in the amount of heat. "I will not pretend to determine how far this may assist in keeping up the animal heat." Observations on the Structure and Economy of Whales, in Hunter's Works, vol. iv. p. 364.

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