It would be difficult to determine how large a portion of the facts of.medical science now most familiarly known we owe to the extra ordinary labours of Haller. Some idea of the extent of his works may be formed from the fact that the titles of nearly two hundred treatises published by him from 1727 to 1777 are given by Senebier in his Eloge' of Haller, and that this list does not profess to be complete. He is unanimously received as the father of modern physiology, the history of which, in fact, commences with his writings. He was the first to investigate independently the laws of the animal economy, which had before been studied only in connection with the prevailing mechanical and chemical or metaphysical theories of the day. Com mencing with a sound knowledge of anatomy, and of the structure of the organs in the dead body, he sought experimentally aud systemati cally to discover the laws which governed their actions during life, proceeding from the most simple to the most complex phenomena. Excluding all the metaphysical explanations which Van Helmont and Stahl had invented, and all those deduced from mechanics and chemistry which were not clearly sufficieut for the phenomena ascribed to them, he. sought for powers peculiar to the living body, which he believed must govern the actions which ho found occurring only in it. These he thought might be restricted to two—sensibility and irrita bility; the former seated in the brain and nerves, the latter in muscular fibre. In this he had indeed been partially anticipated by Glisson [GLissoN], who perceived the necessity of admitting an inherent property in muscular fibre, by which its contractions tako place under the influence of certain stimuli ; but the laws of this property, and the distinction between it and elasticity, had never beeu at all clearly determioed. Haller thus illustrated these properties : the intestine removed from the abdomen, or a muscle separated from the body, is irritable, for when pricked or otherwise stimulated it contracts—yet it is not sensible; the nerves on the other hand are sensible, but not irritable, for when stimulated, though the muscles to which they are distributed are thrown into action, they themselves do not exhibit the slightest motion. Hence irritability, he said, cannot be derived from the nerves, for it is impossible they should communicate what they do not possess themselves ; but he attributed a nervous power to some of the muscles as a necessary conditiou of their irritability, and sup posed it to be conveyed to them during life from the brain through the nerves, and to govern their actions under the influence of certain undetermined lawa. Proceeding to investigate further the laws of irritability, he found that it differed in intensity and permanency in different parts of the body. He found that it continued longest in the left ventricle of tho heart, next in the intestines and the diaphragm, and that it ceased soonest of all in the voluntary muscles, and by reference to this superior degree of irritability he explained the con stant action of the heart and diaphragm even during sleep. Ho denied all irritability to the iris, and believed that the action of light upon it takes place through the medium of the retina—a view since proved to be correct. He supposed the arteries to be supplied with muscular fibres, but that the cellular tissue around them prevented any motion from taking place in them ; and he explained the accumulation of blood in an inflamed part, partly by the cootractiou of the veins and partly by the diminished contractility of the arteries. He endeavoured to prove by experiments that the tendons, the capsules of joints, the periosteum, and tho data mater, are entirely insensible, and that tho pain which occura in diseases of these parts ought to be referred to the affection of the nerves distributed to aud around them; and in these and some other tissues which he held to be destitute of irrita bility he admitted a force analogous to elasticity, by which they contracted slowly and in a manner altogether different from muscular tissue when divided or exposed to cold, &c.
Such is a sketch of the great doctrine of irritability and sensibility on which Haller based all the phenomena of life, and around which ho arranged all the facts of physiology known at his time in his 'Eledaeuta Physiologic's.' It gave the first impulse to the study of the laws of life as a separate and exclusive science; and though in some parts erro neous, aud in many Insufficient, it still contained enough of truth to form a firm basis for the observations collected during many successive years. His doctrines were strongly opposed by Whytt and others, and in the controversies that followed numerous new facts were advanced and the most important additions to physiological knowledge rapidly made. It was soon shown that the restriction of the vital powers to the two, as defined by Haller, was much too exclusive, for that there were many parts which, though they gave no evidence of possessing either of them, were not the less alive; while others to which Haller refused these properties gave sufficient demonstration of possessing them when excited by other and appropriate stimuli. Hence first originated the discovery of the fact that for the action of each organ a peculiar stimulus is required, and that each tissue has what Bichat, who illustrated it most completely, called a vie propre.'
But even if Haller had not attempted to establish any such great generalisation of vital phenomeua as this, his learning and his admirable mode of studying physiology might have been sufficient to obtain for him a reputation nearly as high as that which he has always enjoyed. Possessed of a competent knowledge of all the sciences which could throw any light on the actions occurring in the living body, he pointed out In numberless instances what part of them was to be attributed to the laws of iuorganio matter and what to those peculiar to the state of life, while he carefully avoided admitting any of the former as sufficient by themselves to explain the of the latter, which had been the chief error of nearly all his predeeessors. Ile rarely drew any conclusion respecting the mode of action of any organ or part in the human body without previously investigating the analogous function in the bodies of animals by dissection or experi ment, and be tells us that he often found that questions to which no sufficient answers could be obtained b7 observations on the human body, were at once solved by his examinations in the various classes of animal,. Deeply read to all the works of those who preceded him, and in all those of his contemporaries in every nation, he did nut attempt to decide anything till he had considered all their statements and compared them with his own investigations; and hence each of his works contains so perfect an epitome of the Isbuurs of all former writers on the same subject, and a masa of evidence so exteosive, that whatever errors the conclusions he sometimes arrived at may contain, they can never fail to be records of the highest value. At the same time the elegant and lucid style in which they are written, the result of the combination, almost unique, of the poot with the anatomist, has rendered them attractive, notwithstandiog their great extent, to his successors in every country.
Hailer was fortunate in receiving the high honours which In deserved during his life-time. In 1739 he was appointed physician to the King of England. In 1743 he was elected a Fellow of the Royal Society of London, and at different times subsequently of all the scientific societies of Europe. When George II. visited Gottingeo in 1748 he was ennobled by the emperor; he was invited by Frederick the Great to settle in Berlin, with a handsome salary, to which no duties were attached, and was offered a professorship at Oxford and at Utrecht. lie enjoyed throughout his life tho friendship and esteem of the most eminent of his contemporaries throughout Europe; and, varied as his pursuits were, he acquitted himself in all with the highest honour and euccess. It would be impossible here to give a complete list of his original writings and compilations ; few writers have ever been so voluminous; and it is extraordinary that, amidst all his personal and laborious investigations, he should have had oppor tunity for the composition of so extensive a library as they alone would form. A large portion were probably formed from tho seen mutation of notes which he had made in following out his system of invariably recording everything which appeared to him worthy of notice ; a plan which, commenced, as we have seen, in childhood, he continued without intermission to the last years of his life. The following are his principal works:— His chief political production, 'Versuch Sehweizerischer Gedichte,' was published anonymously at Berne ; afterwards two more editions of it were printed there, and four at Gittingen. Three editions of a French translation were also published. From 1750 to 1760 he was engaged in publishing, in 19 vols. 4to, a number of the most select disputations and theses in anatomy, surgery, and medicine ; and from 1757 to 1766 hie Elementa Physiologho Corporis llumani,' undoubtedly the greatest work on medical science which the 18th century produced. It contains every fact and every doctrine of physiology at that time known, and is written in such a style of elegance and classical beauty that it is still a model for writers on the same subject It appeared in 8 vols. 4to from 1757 to 1766, and a posthumous 'Auctarium ' was published in 1782 in four 4to faeciculi. From 1774 to the time of his death he was engaged iu publishing part of his ' Bibliotheete Anatomise, Chirurgice, MediCill£0 Practices, liotaui cse, et Histories Naturalist,' which form altogether 10 vole. Ito, of which the publication was completed posthumously. They are composed principally of abstracts of the writings of all the most esteemed authors on each subject, so as to form a complete history of the doctrines of each science. His ' Icones Anatomise; which were published from 1743 to 1756, contain most accurate and well-engraved representations of the principal organs of the body, especially of the arteries. The greater part of his contributions to the various scientific transactions, and of his shorter works, were collected in his 'Opera Minors,' iu 3 cols. 40, from 1762 to 1768. The most valuable of the papers contained in them are those on the Development of the Chick, on the Formation of the Heart and the Bones;on the Circulation, and on the Eye.
(Das Leber, (k1 Herrn ron Ilaller, von J. 0, Zimmermann, 1 vol.8vo, 1755; Senctsier, Eloge de Haller, Geneva, 1778; 1 lietoire de to AI edeeine, par K. Sprengel.)