If now we look at the organs by which in man the functions of these two lives are carried on, we shall be struck by the remarkable fact, that the organs of his vegetable life are very irregular, those of his animal life very symmetrical. His vegetative, or organic, life is conducted by the stomach, the intestines, and the glandular system in general, such as the liver and the pancreas; all of which are irregular, and admit of the greatest variety of form and development, without their functions being seriously disturbed. But in his animal life the organs are so essentially symmetrical, that a very slight departure from the ordinary type impairs their action. 162 Not only the brain, but also the organs of sense, as the eyes, the nose, the ears, are perfectly symmetrical; and they as well as the other organs of animal life, as the feet and hands, are double, presenting on each side of the body two separate parts which correspond with each other, and produce a symmetry unknown to our vegetative life, the organs of which are, for the most part, merely single, as in the stomach, liver, pancreas, and spleen.163

From this fundamental difference between the organs of the two lives, there have arisen several other differences of great in

162 "C'est de là, sans doute, que naît cette autre différence entre les organes des deux vies, savoir, que la nature se livre bien plus rarement à des écarts de conformation dans la vie animale que dans la vie organique... C'est une remarque qui n'a pu échapper à celui dont les dissections ont été un peu multipliées, que les fréquentes variations de formes, de grandeur, de position, de direction des organes internes, comme la rate, le foie, l'estomac, les reins, les organes salivaires, etc. . . . Jetons maintenant les yeux sur les organes de la vie animale, sur les sens, les nerfs, le cerveau, les muscles volontaires, le larynx; tout y est exact, précis, rigoureusement déterminé dans la forme, la grandeur, et la position. On n'y voit presque jamais de variété de conformation; s'il en existe, les fonctions sont troublées, anéanties; tandis qu'elles restent les mêmes dans la vie organique, au milieu des altérations diverses des parties." Bichat sur la Vie, pp. 23-25. Part of this view is corroborated by the evidence collected by Saint Hilaire (Anomalies de l'Organisation, vol. i. pp. 248, seq.) of the extraordinary aberrations to which the vegetative organs are liable; and he mentions (vol. ii. p. 8) the case of a man, in whose body, on dissection, on reconnut que tous les viscères étaient transposés." Comparative anatomy supplies another illustration. The bodies of mollusca are less symmetrical than those of articulata; and in the former, the "vegetal series of organs," says Mr. Owen, are more developed than the animal series; while in the articulata, “the advance is most conspicuous in the organs peculiar to animal life." Owen's Inverte brata, p. 470. Compare Burdach's Physiologie, vol. i. pp. 153, 189; and a confirmation of the "unsymmetrical" organs of the gasteropoda, in Grant's Comparative Anatomy, p. 461. This curious antagonism is still further seen in the circumstance, that idiots, whose functions of nutrition and of excretion are often very active, are at the same time remarkable for a want of symmetry in the organs of sensation. Esquirol, Maladies Mentales, vol. ii. pp. 331, 332.

A result, though perhaps an unconscious one, of the application and extension of these ideas, is, that within the last few years there has arisen a pathological theory of what are called "symmetrical diseases," the leading facts of which have been long known, but are now only beginning to be generalized. See Paget's Pathology, vol. i. pp. 18-22, vol. ii. pp. 244, 245; Simon's Pathology, pp. 210, 211; Carpenter's Human Physiol. pp. 607, 608.

163 Bichat sur la Vie, pp. 15-21.

Our animal life being double, while our organic life is single, it becomes possible for the former life to take rest, that is, stop part of its functions for a time, and afterwards renew them. But in organic life, to stop is to die. The life, which we have in common with vegetables, never sleeps; and if its movements entirely cease only for a single instant, they cease for ever. That process by which our bodies receive some substances and give out others, admits of no interruption; it is, by its nature, incessant, because, being single, it can never receive supplementary aid. The other life we may refresh, not only in sleep, but even when we are awake. Thus we can exercise the organs of movement while we rest the organs of thought; and it is even possible to relieve a function while we continue to employ it, because, our animal life being double, we are able for a short time, in case of one of its parts being fatigued, to avail ourselves of the corresponding part; using, for instance, a single eye or a single arm in order to rest the one which circumstances may have exhausted; an expedient which the single nature of organic life entirely prevents. 164

Our animal life being thus essentially intermittent, and our organic life being essentially continuous, 165 it has necessarily followed that the first is capable of an improvement of which the second is incapable. There can be no improvement without comparison, since it is only by comparing one state with another that we can rectify previous errors, and avoid future ones. Now, our organic life does not admit of such comparison, because, being uninterrupted, it is not broken into stages, but when unchequered by disease, runs on in dull monotony. On the other hand, the functions of our animal life, such as thought, speech, sight, and motion, cannot be long exercised without rest; and as they are constantly suspended, it becomes practicable to compare them, and, therefore to improve them. It is by possessing this resource that the first cry of the infant gradually rises into the perfect speech of the man, and the unformed habits of early thought are ripened into that maturity which nothing can give but a long series of successive efforts. 166 But our organic life, which we have in common with vegetables, admits of no interruption, and consequently of no improvement. It obeys its own

164 Ibid. pp. 21-50.

166 On intermittence as a quality of animal life, see Holland's Medical Notes, pp. 313, 314, where Bichat is mentioned as its great expounder. As to the essential continuity of organic life, see Burdach's Physiologie, vol. viii. p. 420. M. Comte has made some interesting remarks on Bichat's law of intermittence. Philos. Positive, vol. iii. pp. 300, 395, 744, 745, 750, 751,

166 On the development arising from practice, see Bichat sur la Vie, pp. 207

laws; but it derives no benefit from that repetition to which animal life is exclusively indebted. Its functions, such as nutrition and the like, exist in man several months before he is born, and while, his animal life not having yet begun, the faculty of comparison, which is the basis of improvement, is impossible.167 And although, as the human frame increases in size, its vegetative organs become larger, it cannot be supposed that their functions really improve, since, in ordinary cases, their duties are performed as regularly and as completely in childhood as in middle age.168

Thus it is, that although other causes conspire, it may be said that the progressiveness of animal life is due to its intermittence; the unprogressiveness of organic life to its continuity. It may, moreover, be said, that the intermittence of the first life results from the symmetry of its organs, while the continuity of the second life results from their irregularity. To this wide and striking generalization, many objections may be made, some of them apparently insuperable; but that it contains the germs of great truths I entertain little doubt, and, at all events, it is certain that the method cannot be too highly praised, for it unites the study of function and structure with that of embryology, of vegetable physiology, of the theory of comparison, and of the influence of habit; a vast and magnificent field, which the genius of Bichat was able to cover, but of which, since him, neither physiologists nor metaphysicians have even attempted a general survey.

This stationary condition, during the present century, of a subject of such intense interest, is a decisive proof of the extraordinary genius of Bichat; since, notwithstanding the additions made to physiology, and to every branch of physics connected with it, nothing has been done at all comparable to that theory of life which he, with far inferior resources, was able to construct. This stupendous work he left, indeed, very imperfect; but even in its deficiencies we see the hand of the great master, whom, on

167 Ibid. pp. 189-203, 225-230. M. Broussais also (in his able work, Cours de Phrenologie, p. 487) says, that comparison begins only after birth; but surely this must be very doubtful. Few physiologists will deny that embryological phenomena, though neglected by metaphysicians, play a great part in shaping the future character; and I do not see how any system of psychology can be complete which ignores considerations, probable in themselves, and not refuted by special evidence. So carelessly, however, has this subject been investigated, that we have the most conflicting statements respecting even the vagitus uterinus, which, if it exists to the extent alleged by some physiologists, would be a decisive proof that animal life (in the sense of Bichat) does begin during the foetal period. Compare Burdach, Physiol. vol. iv. pp. 113, 114, with Wagner's Physiol, p. 182.

168 "Les organes internes qui entrent alors en exercice, ou qui accroissent beaucoup leur action, n'ont besoin d'aucune éducation; ils atteignent tout à coup une perfection à laquelle ceux de la vie animale ne parviennent que par habitude d'agir souvent." Bichat sur la Vie, p. 231.

his own subject, no one has yet approached. His essay on life may well be likened to those broken fragments of ancient art, which, imperfect as they are, still bear the impress of the inspiration which gave them birth, and present in each separate part that unity of conception which to us makes them a complete and living whole.

From the preceding summary of the progress of physical knowledge, the reader may form some idea of the ability of those eminent men who arose in France during the latter half of the eighteenth century. To complete the picture, it is only necessary to examine what was done in the two remaining branches of natural history, namely, botany and mineralogy, in both of which the first great steps towards raising each study to a science were taken by Frenchmen a few years before the Revolution.

In botany, although our knowledge of particular facts has, during the last hundred years, rapidly increased,169 we are only possessed of two generalizations wide enough to be called laws of nature. The first generalization concerns the structure of plants; the other concerns their physiology. That concerning their physiology is the beautiful morphological law, according to which the different appearance of the various organs arises from arrested development: the stamens, pistils, corolla, calyx, and bracts, being simply modifications or successive stages of the leaf. This is one of many valuable discoveries we owe to Germany; it being made by Göthe late in the eighteenth century.170 With its importance every botanist is familiar; while to the historian of the human mind it is peculiarly interesting, as strengthening that great doctrine of development, towards which the highest branches of knowledge are now hastening, and which, in

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169 Dioscorides and Galen knew from 450 to 600 plants. Winckler, Geschichte der Botanik, 1854, pp. 34, 40; but, according to Cuvier (Eloges, vol. iii. p. 468), Linnæus, in 1778, en indiquait environ huit mille espèces ;" and Meyen (Geog. of Plants, p. 4) says, "at the time of Linnæus's death, about 8000 species were known." (Dr. Whewell, in his Bridgewater Treatise, p. 247, says “about 10,000.") Since then the progress has been uninterrupted; and in Henslow's Botany, 1837, p. 136, we are told that "the number of species already known and classified in works of botany amounts to about 60,000." Ten years later, Dr. Lindley (Vegetable Kingdom, 1847, p. 800) states them at 92,930; and two years afterwards, Mr. Balfour says "about 100,000." Balfour's Botany, 1849, p. 560. Such is the rate at which our knowledge of nature is advancing. To complete this historical note, I ought to have mentioned, that in 1812, Dr. Thomson says "nearly 30,000 species of plants have been examined and described." Thomson's Hist. of the Royal Society, p. 21.

170 It was published in 1790. Winckler, Gesch. der Botanik, p. 389. But the historians of botany have overlooked a short passage in Göthe's works, which proves that he had glimpses of the discovery in or before 1786. See Italianische Reise, in Gothe's Werke, vol. ii. part ii. p. 286, Stuttgart, 1837, where he writes from Padua, in September, 1786, "Hier in dieser neu mir entgegen tretenden Mannigfaltigkeit wird jener Gedanke immer lebendiger: dass man sich alle Pflanzengestalten vielleicht aus Einer entwickeln könne." There are some interesting remarks on this brilliant generalization in Owen's Parthenogenesis, 1849, pp. 53 seq.

the present century, has been also carried into one of the most difficult departments of animal physiology.11

But the most comprehensive truth with which we are acquainted respecting plants, is that which includes the whole of their general structure; and this we learnt from those great Frenchmen who, in the latter half of the eighteenth century, began to study the external world. The first steps were taken directly after the middle of the century, by Adanson, Duhamel de Monceau, and, above all, Desfontaines; three eminent thinkers, who proved the practicability of a natural method hitherto unknown, and of which even Ray himself had only a faint perception. 172 This, by weakening the influence of the artificial system of Linnæus,173 prepared the way for an innovation more complete than has been effected in any other branch of knowledge. In the very year in which the Revolution occurred, Jussieu put forward a series of botanical generalizations, of which the most important are all intimately connected, and still remain the highest this department of inquiry has reached.174 Among these,

171 That is, into the study of animal monstrosities, which, however capricious they may appear, are now understood to be the necessary result of preceding events. Within the last thirty years several of the laws of these unnatural births, as they used to be called, have been discovered; and it has been proved that, so far from being unnatural, they are strictly natural. A fresh science has thus been created, under the name of Teratology, which is destroying the old lusus naturæ in one of its last and favourite strongholds.

172 Dr. Lindley (Third Report of Brit. Assoc. p. 33) says, that Desfontaines was the first who demonstrated the opposite modes of increase in dycotyledonous and monocotyledonous stems. See also Richard, Eléments de Botanique, p. 131; and Cuvier, Eloges, vol. i. p. 64. In regard to the steps taken by Adanson and De Monceau, see Winckler, Gesch. der Botanik, pp. 204, 205; Thomson's Chemistry of Vegetables, p. 951; Lindley's Introduc. to Botany, vol. ii. p. 132.

173 It is curious to observe how even good botanists clung to the Linnæan system long after the superiority of a natural system was proved. This is the more noticeable, because Linnæus, who was a man of undoubted genius, and who possessed extraordinary powers of combination, always allowed that his own system was merely provisional, and that the great object to be attained was a classification according to natural families. See Winckler, Geschichte der Botanik, p. 202; Richard, Eléments de Botanique, p. 570. Indeed, what could be thought of the permanent value of a scheme which put together the reed and the barberry, because they were both hexandria; and forced sorel to associate with saffron, because both were trigynia? Jussieu's Botany, 1849, p. 524.

174 The Genera Plantarum of Antoine Jussieu was printed at Paris in 1789; and, though it is known to have been the result of many years of continued labour, some writers have asserted that the ideas in it were borrowed from his uncle, Bernard Jussieu. But assertions of this kind rarely deserve attention; and as Bernard did not choose to publish any thing of his own, his reputation ought to suffer for his uncommunicativeness. Compare Winckler, Gesch. der Botanik, pp. 261-272, with Biog. Univ. vol. xxii. pp. 162-166. I will only add the following remarks from a work of authority, Richard, Elements de Botanique, Paris, 1846, p. 572: "Mais ce ne fut qu'en 1789 que l'on eut véritablement un ouvrage complet sur la méthode des familles naturelles. Le Genera Plantarum d'A. L. de Jussieu présenta la science des végétaux sous un point de vue si nouveau, par la précision et l'élégance qui y règnent, par la profondeur et la justesse des principes généraux qui y sont exposés pour la première fois, que c'est depuis cette époque seulement que la méthode des