John gradually became led into the study of comparative anatomy, from finding that structures which were complex in the human subject were simpler in animals, or different in plan, in both cases throwing light on human anatomy and physiology. Thus he made dissections of all the commoner animals, and always preserved the parts which interested him. He soon passed beyond the ordinary range, and made acquaintance with the keeper of the Tower menagerie, that he might obtain the bodies of such animals as died there. Similarly he even would purchase animals when alive, from travelling showmen, simply requiring them to bring him their bodies whenever they happened to die. He bought all rare animals that came in his way: others were presented to him by friends, and thus an ample supply of material was secured.
There is some obscurity about the reasons which induced the younger brother in 1760 to accept an appointment as staff-surgeon in the army, joining the expedition to Belleisle in 1761. There is not much doubt, however, that his health had suffered, and that a foreign voyage and residence were calculated to restore him. In 1762 he was employed with the army in Portugal, and in this experience laid the foundation of his knowledge of military surgery. During this expedition he neglected no opportunity of forwarding his studies in comparative anatomy and physiology. Thus when at Belleisle, in order to discover whether animals in a state of hibernation could digest food, he introduced worms and pieces of meat into the stomachs of lizards, and kept them under observation in a cool place. He found the substances so introduced remained perfectly undigested. So in 1762, near Lisbon, he tested the hearing of fishes by observing the effect of the report of a gun upon the inhabitants of a nobleman’s fish-pond.
Retiring from the army after the peace of 1763, John Hunter found his place in his brother’s dissecting-room occupied by Mr. Hewson, a most capable dissector and lecturer. Hence he had no option but to depend on his own exertions, and he started in London practice as a surgeon in Golden Square. He found that practice came but slowly, and formed a class for the study of anatomy and practical surgery to add to his income. This, too, never proved nearly so remunerative as his brother’s lectures, owing to John’s defects of style and expression already mentioned. His success in practice was also retarded by his refusal or failure to employ any of the arts or tact needed to gain personal popularity. Although he was a good convivial companion, at any rate in his earlier days, any festive enjoyment was always subordinated to his zeal for a new specimen or a rare case, from which he could learn something. He would take any trouble, or go any distance, with these ends in view; while his feeling about an ordinary case may be gathered from a remark to his attached friend, Lynn, as he laid aside his dissecting instruments—“Well, Lynn, I must go and earn this d--d guinea, or I shall be sure to want it to-morrow.” Mere fashionableness Hunter could not tolerate. Dr. Garthshore, a physician of the old school, always formal, polite, and well dressed, accosting him one day in his dissecting-room with his usual empressement, “My d-e-a-r John Hunter,”—was astonished to hear the mocking reply, “My d-e-a-r Tom Fool.” The busy dissector was not likely to value highly the formalities of the courtly doctor, who as a contemporary remarks, “occasionally looked in, wound up his watch, and fell asleep.”
Finding his collection of live animals grow beyond his means of providing for them in town, Hunter purchased a considerable piece of ground at Earl’s Court, then about two miles outside London, and built upon it a house with a lawn behind it, upon and around which he kept a collection of curious variety, and sometimes under comparatively slight control, in order that their habits might the more readily be watched. On one occasion two leopards got loose, and one was scaling the boundary wall, while the other was engaged in combat with dogs, when Mr. Hunter, unarmed, went out and seized them both and replaced them in their outhouse; an act of courage which, when it was over, nearly caused him to faint.
In 1767 an accident by which Mr. Hunter ruptured his tendo Achillis, whether while dancing, or in getting up from the dissecting-table after being cramped by long sitting, is not certain, occasioned him to study carefully the process by which ruptured tendons are healed. His method of treating himself was to keep the heel raised, and to compress the muscle gently with a roller, thus preventing any spasmodic contraction. He divided the same tendon in several dogs, killing them subsequently at different periods to examine the progress and nature of the repair; and his experiments and specimens were the origin of the present practice of cutting through tendons for the relief of distorted and contracted joints.
In the same year, 1767, Mr. Hunter was elected into the Royal Society, before his brother—an evidence that his eager investigations were already making him well known to men of inquiring minds. At a later period he was one of the originators of meetings at a coffee-house to discuss papers before their submission to the Society generally. In 1768 he became a member of the Royal College of Surgeons, and in the same year, supported by his brother’s interest, he was elected surgeon to St. George’s Hospital by 114 to 42 votes. He was now in a position in which more patients were at his disposal for experimental or novel modes of treatment, and in which he could take resident pupils on advantageous terms. In 1770 his brother’s removal to his new premises in Great Windmill Street, led to John’s transfer to his brother’s late house in Jermyn Street, where he found much more ample accommodation for his work than he had hitherto possessed. Here among his earliest pupils was Dr. Jenner, who was an enthusiastic disciple, and whom Mr. Hunter would gladly have permanently associated with him. He kept up a continual and intimate correspondence with him throughout life, often asking Dr. Jenner for information on questions of natural history.
Soon after his removal to Jermyn Street, namely, in July 1771, Mr. Hunter married Anne, eldest daughter of Mr. Robert Home, an army surgeon, father of his subsequent pupil and associate, Sir Everard Home. He had been engaged to Miss Home for some years, but financial reasons had hitherto postponed the marriage. Mrs. Hunter had artistic, literary, and musical tastes, which to some extent, by their expense, trenched on her husband’s scientific objects. She is remembered as the author of the words of a number of Haydn’s English canzonets, including the celebrated one, “My mother bids me bind my hair.” Mr. Hunter sometimes found that his wife’s friends were too fashionable or frivolous for his taste, and occasionally his irritation got the better of his manners. It is related that once, returning late in the evening after a wearisome day’s work, he unexpectedly found his drawing-room filled with gay company, walked straight into the room, and addressed the assembly in these terms: “I knew nothing of this kick-up, and I ought to have been informed of it beforehand; but as I am now returned home to study, I hope the present company will now retire:” a hope speedily realised. Hunter much preferred the weekly social assemblies at which his scientific friends were welcomed, and where the conversation was pointed and informing. Still there is no ground for reflecting on the general happiness of Mr. Hunter’s married life. Of his two children who survived infancy, he often said that if he had been allowed to bespeak a pair of children, they should have been those with which Providence had favoured him. His wife survived him till 1821, when she died in her 79th year.
Early in 1771 Mr. Hunter published his first work of any magnitude, the first part of his “Treatise on the Natural History of the Human Teeth,” which long continued a standard work, largely appropriated by subsequent writers. The second part, treating of the diseases of the teeth, did not appear till 1778. In 1772 he made his mark at the Royal Society by his celebrated paper on the digestion of the stomach after death, which he attributed to the action of the gastric juice upon the dead tissues. His stores of knowledge and learning were afterwards made evident by many papers in the “Philosophical Transactions,” of which the principal were those on the torpedo (1773), on the air receptacles of birds, and on the Gillaroo trout, 1774; the production of heat by animals and vegetables, 1775; the recovery of persons apparently drowned, 1776; the communication of smallpox to the fœtus in utero, 1780; the organ of hearing in fishes, 1782; the specific identity of the wolf, jackal, and dog, and on the structure and economy of whales, 1787; observations on bees, 1793; and on some remarkable caves in Bayreuth, and fossil bones found therein, 1794. The titles of these papers, however, convey but a very imperfect idea of the wide range of subjects treated in them. When he described a structure, he made it the starting-point of a dissertation, in the course of which he brought to bear all his vast stores of knowledge to establish general principles or to illustrate important points of physiology.
In the autumn of 1772 his brother-in-law, Everard Home, became his pupil. He describes Hunter’s museum at this time as already having an imposing magnitude. All the best rooms in the house were devoted to it, and it was continually being enlarged by his unremitting toil. From six, or earlier, till nine, when he breakfasted, Hunter dissected; after breakfast till twelve he was at home to patients. Punctuality he observed to a fault. He would leave patients at home in order to start punctually to his outside consultations, “for,” said he, “these people can take their chance another day, and I have no right to waste the valuable time of other practitioners by keeping them waiting for me.” He kept one book at home in which to enter these, and had an exact copy of it always in his waistcoat pocket: thus those at home by referring to the book could invariably find him. Once his former pupil, Cline, having to meet Hunter in consultation, made a second arrangement, unknown to Hunter, to take him to see another patient of his immediately after. Hunter’s outburst of passion at this unjustifiable disturbance of his arrangements for the afternoon was with difficulty appeased. His punctuality at dinner, at four, was equally settled, but he strictly ordered that dinner should be served whether he were at home or not. For many years he drank no wine, and sat but a short time at table, except when he had company; but he nevertheless pressed the guests to disregard his example. “Come, fellow,” said he, in his usual blunt way, to Mr., afterwards Sir William, Blizard, “why don’t you drink your wine?” The guest pleaded in excuse a whitlow, which caused him much pain. Hunter would not allow the validity of the plea, but continued to urge him and ridicule his excuse. “Come, come, John,” said Mrs. Hunter, “you will please to remember that you were delirious for two days when you had a boil on your finger some time ago.” This turned the laugh against Hunter, who ceased to importune his guest.
In addition to his own pre-eminent industry, Hunter was not without the most important talent of making others’ labours advance his ends. Thus for fourteen years he employed a very capable young artist named Bell, keeping him resident in his house, occupied in making drawings, and anatomical preparations, and generally in museum work. Bell was frequently called in also to act as Hunter’s amanuensis. After he left Mr. Hunter, in 1789, he became an assistant-surgeon under the East India Company, settling at Bencoolen, where his zoological studies were continued with much promise of great achievement; but, unfortunately for science, he died of fever in 1792.