moisture, air, and temperature; also the way in which their prop erties are altered by various chemical substances, 145 and even their effect on the taste.146 By these means, and by many other experiments tending in the same direction, he took so great and sudden a step, that he is to be regarded not merely as an innovator on an old science, but rather as the creator of a new one.147 And although subsequent observers have corrected some of his conclusions, this has only been done by following his method; the value of which is now so generally recognized, that it is adopted by nearly all the best anatomists, who, differing in other points, are agreed as to the necessity of basing the future progress of anatomy on a knowledge of the tissues, the supreme importance of which Bichat was the first to perceive.148

The methods of Bichat and of Cuvier, when put together,

anatomy," and "structural development," are to be made the foundations of pathol ogy, is, moreover, observed in Simon's Pathology, 1850, p. 115 (compare Williams's Principles of Medicine, 1848, p. 67), who ascribes the chief merit of this "rational pathology" to Henle and Schwann; omitting to mention that they only executed Bichat's scheme, and (be it said with every respect for these eminent men) executed it with a comprehensiveness much inferior to that displayed by their great predecessor. In Broussais, Examen des Doctrines Médicales, vol. iv. pp. 106, 107, there are some just and liberal observations on the immense service which Bichat rendered to pathology. See also Béclard, Anatomie, Paris, 1852, p. 184.

145 Bichat, Anat. Gen. vol. i. pp. 51, 160, 161, 259, 372, vol. ii. pp. 47, 448, 449, vol. iii. pp. 33, 168, 208, 309, 406, 435, vol. iv. pp. 21, 52, 455-461, 517.

146 According to M. Comte (Philos. Pos. vol. iii. p. 319), no one had thought of this before Bichat. MM. Robin et Verdeil, in their recent great work, fully admit the necessity of employing this singular resource. Chimie Anatomique, 1853, vol. i. pp. 18, 125, 182, 357, 581.

147 Dès-lors il créa une science nouvelle, l'anatomie générale." Pinel sur Bichat, p. xii. "A Bichat appartient véritablement la gloire d'avoir concu et surtout exécuté, le premier, le plan d'une anatomie nouvelle." Bouillaud, Philos. Médicale, p. 27. "Bichat fut le créateur de l'histologie, en assignant des caractères précis à chaque classe de tissus." Burdach, Physiologie, vol. vii. p. 111. "Le créateur de l'anatomie générale, fut Bichat." Henle, Anatomie, vol. i. p. 120. Similar remarks will be found in Saint Hilaire, Anomalies de l'Organisation, vol. i. p. 10; and in Robin et Verdeil, Chimie Anat. vol. i. p. xviii., vol. iii. p. 405.

148 In Béclard, Anat. Gén. 1852, p. 61, it is said that "la recherche de ces tissus élémentaires, ou éléments organiques, est devenue la préoccupation presque exclusive des anatomistes de nos jours." Compare Blainville, Physiol. Gen. et Comp. vol. i. p. 93: "Aujourd'hui nous allons plus avant, nous pénétrons dans la structure intime, non seulement de ces organes, mais encore des tissus qui concourent à leur composi tion; nous faisons en un mot de la véritable anatomie, de l'anatomie proprement dite." And at p. 105: "c'est un genre de recherches qui a été cultivé avec beau coup d'activité, et qui a reçu une grande extension depuis la publication du bel ouvrage de Bichat." See also vol. ii. p. 303.

In consequence of this movement, there has sprung up, under the name of De generations of Tissues, an entirely new branch of morbid anatomy, of which, I be lieve, no instance will be found before the time of Bichat, but the value of which is now recognized by most pathologists. Compare Paget's Surgical Pathology, vol. i. pp. 98-112; Williams's Principles of Medicine, pp. 369-376; Burdach's Physiologie, vol. viii. p. 367; Reports of Brit. Assoc. vol. vi. p. 147; Jones and Sieveking's Pathological Anatomy, 1854, pp. 154-156, 302-304, 555-558. "They are," say these last writers," of extremely frequent occurrence; but their nature has scarcely been recognized until of late."

exhaust the actual resources of zoological science, so that all subsequent naturalists have been compelled to follow one of these two schemes; that is, either to follow Cuvier in comparing the organs of animals, or else to follow Bichat in comparing the tissues which compose the organs.149 And inasmuch as one comparison is chiefly suggestive of function, and the other comparison of structure, it is evident, that to raise the study of the animal world to the highest point of which it is capable, both these great plans are necessary: but if we ask which of the two plans, unaided by the other, is more likely to produce important results, the palm must, I think, be yielded to that proposed by Bichat. Certainly, if we look at the question as one to be decided by authority, a majority of the most eminent anatomists and physiologists now incline to the side of Bichat, rather than to that of Cuvier; while, as a matter of history, it may be proved that the reputation of Bichat has, with the advance of knowledge, increased more rapidly than that of his great rival. What, however, appears to me still more decisive, is, that the two most important discoveries made in our time respecting the classification of animals, are entirely the result of the method which Bichat suggested. The first discovery is that made by Agassiz, who, in the course of his ichthyological researches, was led to perceive that the arrangement by Cuvier according to organs, did not fulfil its purpose in regard to fossil fishes, because in the lapse of ages the characteristics of their structure were destroyed.150 He, therefore, adopted the only other remaining plan, and studied the tissues, which, being less complex than the organs, are oftener found intact. The result was the very remarkable discovery, that the tegumentary membrane of fishes is so intimately connected with their organization, that if the whole of a fish has perished except this membrane, it is practicable, by noting its characteristics, to reconstruct the animal in its most essential parts. Of the value of this principle of harmony, some idea may be formed from the circumstance, that on it Agassiz has based the whole of that celebrated classification, of which he is the sole author, and by which fossil ichthyology has for the first time assumed a precise and definite shape.151

149 Cuvier completely neglected the study of tissues; and in the very few instances in which he mentions them, his language is extremely vague. Thus, in his Règne Animal, vol. i. p. 12, he says of living bodies, "leur tissu est donc composé de réseaux et de mailles, ou de fibres et de lames solides, qui renferment des liquides dans leurs intervalles."

160 A well-known ornithologist makes the same complaint respecting the classifi cation of birds. Strickland on Ornithology, Brit. Assoc. for 1844, pp. 209, 210. Even in regard to living species, Cuvier (Règne Animal, vol. ii. p. 128) says, "La classe des poissons est de toutes, celle qui offre le plus de difficultés quand on veut la subdiviser en ordres d'après des caractères fixes et sensibles."

151 The discoveries of M. Agassiz are embodied in his great work, Recherches sur

The other discovery, of which the application is much more extensive, was made in exactly the same way. It consists of the striking fact, that the teeth of each animal have a necessary connexion with the entire organization of its frame; so that, within certain limits, we can predict the organization by examining the tooth. This beautiful instance of the regularity of the operations of nature was not known until more than thirty years after the death of Bichat, and it is evidently due to the prosecution of that method which he sedulously inculcated. For the teeth never having been properly examined in regard to their separate tissues, it was believed that they were essentially devoid of structure, or, as some thought, were simply a fibrous texture. 15 But by minute microscopic investigations it has been recently ascertained that the tissues of the teeth are strictly analogous to those of other parts of the body;153 and that the ivory, or dentine, as it is now called,154 is highly organized; that it, as well as the enamel, is cellular, and is, in fact, a development of the living pulp. This discovery, which, to the philosophic anatomist, is pregnant with meaning, was made about 1838; and though the preliminary steps were taken by Purkinjé, Retzius, and Schwann, the principal merit is due to Nasmyth and Owen, 155 between whom it is disputed, but whose rival claims we are not here called upon to adjust.156 What I wish to observe is, that the les Poissons fossiles: but the reader who may not have an opportunity of consulting that costly publication, will find two essays by this eminent naturalist, which will give an idea of his treatment of the subject, in Reports of British Assoc. for 1842, pp. 80-88, and for 1844, pp. 279-310. How essential this study is to the geologist, appears from the remark of Sir R. Murchison (Siluria, 1854, p. 417), that "fossil fishes have every where proved the most exact chronometers of the age of rocks."

152 That they were composed of fibres, was the prevailing doctrine, until the discovery of their tubes, in 1835, by Purkinjé. Before Purkinjé, only one observer, Leeuwenhoek, had announced their tubular structure; but no one believed what he said, and Purkinjé was unacquainted with his researches. Compare Nasmyth's Researches on the Teeth, 1839, p. 159; Owen's Odontography, 1840-1845, vol. i. pp. ix. x.; Henle, Anat. Gen. vol. ii. p. 457; Reports of Brit. Assoc. vol. vii. pp. 135, 136 (Transac. of Sections).

153

Mr. Nasmyth, in his valuable, but, I regret to add, posthumous work, notices, as the result of these discoveries, "the close affinity subsisting between the dental and other organized tissues of the animal frame." Researches on the Development, &c., of the Teeth, 1849, p. 198. This is, properly speaking, a continuation of Mr. Nasmyth's former book, which bore the same title, and was published in 1839.

154 This name, which Mr. Owen appears to have first suggested, has been objected to, though, as it seems to me, on insufficient grounds. Compare Owen's Odontogra phy, vol. i. p. iii., with Nasmyth's Researches, 1849, pp. 3-4. It is adopted in Car penter's Human Physiol. 1846, p. 154; and in Jones and Sieveking's Patholog. Anat. 1854, pp. 483, 486.

165 See the correspondence in Brit. Assoc. for 1841, Sec., pp. 2-23.

156 In the notice of it in Whewell's Hist. of Sciences, vol. iii. p. 678, nothing is said about Mr. Nasmyth; while in that in Wilson's Human Anatomy, p. 65, edit. 1851, nothing is said about Mr. Owen. A specimen of the justice with which men treat their contemporaries. Dr. Grant (Supplement to Hooper's Medical Dict. 1848, p. 1390) says, "the researches of Mr. Owen tend to confirm those of Mr. Nasmyth."

discovery is similar to that which we owe to Agassiz; similar in the method by which it was worked out, and also in the results which have followed from it. Both are due to a recognition of the fundamental maxim of Bichat, that the study of organs must be subordinate to the study of tissues, and both have supplied the most valuable aid to zoological classification. On this point, the service rendered by Owen is incontestable, whatever may be thought of his original claims. This eminent naturalist has, with immense industry, applied the discovery to all vertebrate animals; and in an elaborate work, specially devoted to the subject, he has placed beyond dispute the astonishing fact, that the structure of a single tooth is a criterion of the nature and organization of the species to which it belongs.157

Whoever has reflected much on the different stages through which our knowledge has successively passed, must, I think, be led to the conclusion, that while fully recognizing the great merit of these investigators of the animal frame, our highest admiration ought to be reserved not for those who make the discoveries, but rather for those who point out how the discoveries are to be made.158 When the true path of inquiry has once been indicated, the rest is comparatively easy. The beaten highway is always open; and the difficulty is, not to find those who will travel the old road, but those who will make a fresh one. Every age produces in abundance men of sagacity and of considerable industry, who, while perfectly competent to increase the details of a science, are unable to extend its distant boundaries. This is because such extension must be accompanied by a new method,159 which, to be valuable as well as new, supposes on

Nasmyth, in his last work (Researches on the Teeth, 1849, p. 81), only refers to Owen to point out an error; while Owen (Odontography, vol. i. pp. xlvi-lvi.) treats Nasmyth as an impudent plagiarist.

157 Dr. Whewell (Hist. of Induc. Sciences, vol. iii. p. 678) says, that "he has carried into every part of the animal kingdom an examination, founded upon this discovery, and has published the results of this in his Odontography." If this able, but rather hasty writer, had read the Odontography, he would have found that Mr. Owen, so far from carrying the examination "into every part of the animal kingdom," distinctly confines himself to "one of the primary divisions of the animal kingdom" (I quote his own words from Odontography, vol. i. p. lxvii.), and appears to think, that below the vertebrata, the inquiry would furnish little or no aid for the purposes of classification.

159 But in comparing the merits of discoverers themselves, we must praise him who proves rather than him who suggests. See some sensible remarks in Owen's Odontography, vol. i. p. xlix.; which, however, do not affect my observations on the superiority of method.

159 By a new method of inquiring into a subject, I mean an application to it of generalizations from some other subject, so as to widen the field of thought. To call this a new method is rather vague; but there is no other word to express the process. Properly speaking, there are only two methods, the inductive and the deductive; which, though essentially different, are so mixed together, as to make it impossible wholly to separate them. The discussion of the real nature of this differ

the part of its suggester, not only a complete mastery over the resources of his subject, but also the possession of originality and comprehensiveness,-the two rarest forms of human genius. In this consists the real difficulty of every great pursuit. As soon as any department of knowledge has been generalized into laws, it contains, either in itself or in its applications, three distinct branches; namely, inventions, discoveries, and method. Of these, the first corresponds to art; the second to science; and the third to philosophy. In this scale, inventions have by far the lowest place, and minds of the highest order are rarely occupied by them. Next in the series come discoveries; and here the province of intellect really begins, since here the first attempt is made to search after truth on its own account, and to discard those practical considerations to which inventions are of necessity referred. This is science properly so called; and how difficult it is to reach this stage, is evident from the fact, that all half-civilized nations have made many great inventions, but no great discoveries. The highest, however, of all the three stages, is the philosophy of method, which bears the same relation to science that science bears to art. Of its immense, and indeed supreme importance, the annals of knowledge supply abundant evidence; and for want of it, some very great men have effected absolutely nothing, consuming their lives in fruitless industry, not because their labour was slack, but because their method was sterile. The progress of every science is affected more by the scheme according to which it is cultivated, than by the actual ability of the cultivators themselves. If they who travel in an unknown country, spend their force in running on the wrong road, they will miss the point at which they aim, and perchance may faint and fall by the way. In that long and difficult journey after truth, which the human mind has yet to perform, and of which we in our generation can only see the distant prospect, it is certain that success will depend not on the speed with which men hasten in the path of inquiry, but rather on the skill with which the path is selected for them by those great and comprehensive thinkers, who are as the lawgivers and founders of knowledge; because they supply its deficiencies, not by investigating particular difficulties, but by establishing some large and sweeping innovation, which opens up a new vein of thought, and creates fresh resources, which it is left for their posterity to work out and apply.

It is from this point of view that we are to rate the value of Bichat, whose works, like those of all men of the highest emi

ence I reserve for my comparison, in the next volume, of the German and Ameri san civilizations.