it derives its nourishment from living substances. On this definition follow, as necessary conditions, the capacity of discerning these substances, and the power of procuring them-consequently sensibility and contractibility. To consolidate this, his fundamental analysis of life, the great Bichat was soon compelled to construct an anatomical conception which might be at once its complement and its strictest expression. The cellular tissue alone is universal, and forms the proper seat of vegetable life. Animal life resides in the muscular and nervous tissues. This conception completes the general idea of Biology. It establishes a sufficient agreement between its statical and dynamical point of view to enable us to pass, with propriety, from the function to the organ, and from the organ to the function." [The statical part of the human organism resides in the vegetable, the dynamical in the animal life. As progress is the development of order, so the animal is the development and differentiation of the organic life.] "In obedience to the precept of logic which bids us study all phenomena in the beings where they are most strongly marked, and most free from any complication with higher phenomena, the theory of vegetable life becomes the normal basis of Biology. It establishes directly the general laws of nutrition, by a consideration of the case to which they apply in their simplest and intensest forms. This is the only part of Biology which could be absolutely kept separate from Sociology, were we for a moment to suppose that a subjective arrangement did not direct all objective intellectual cultivation. The theory of vegetable life is the natural transition from matter to life."

Comte has some other observations on this subject in his "Positive Polity," which we cannot do better than quote. We do not wish to abuse the right of quotation, but we would rather be guilty of the abuse than come between Comte and the student save in the way, and that very occasionally, of an humble interpreter. The highest geniuses are alone qualified to speak with authority in profound and complex matters.

"As the vital laws constitute the essential subject of Biology, we must begin by analysing the fundamental idea of life.

"Before the time of Bichat, this idea was wrapped in a mist of metaphysical abstractions; and Bichat himself, after having perceived that a definition of life could be founded

on nothing else than a general view of phenomena, proper to living bodies, so far fell under the influence of the old philosophy as to call life a struggle between dead nature and living nature. The irrationality of this conception consists in its suppressing one of the two elements whose concurrence is necessary to the general idea of life. This idea supposes not only a being so organised as to admit of the vital state, but such an arrangement of external influences as will also admit of it. The harmony between the living being and the corresponding medium (as I shall call its environment) evidently characterises the fundamental condition of life; whereas, on Bichat's supposition, the whole environment of living being tends to destroy them. If certain perturbations of the medium occasionally destroy life, its influence is, on the whole, preservative; and the causes of injury and death proceed, at least, as often from necessary and spontaneous modifications of the organism as from external influences.

"I know of no other successful attempt to define life than that of M. de Blainville, proposed in the introduction to his treatise on Comparative Anatomy. He characterises life as the double interior motion, general and continuous, of composition and decomposition, which, in fact, constitutes its true universal nature. I do not see that this leaves anything to be desired, unless it be a more direct and explicit indication of the two correlative conditions of a determinate organism and a suitable medium. This criticism, however, applies rather to the formula than to the conception, and the conditions are implied in the conception-the conditions of an organism to sustain the renovation, and a medium to minister to the absorption and exhalation; yet it might have been better to express them. With this modification, the definition is unexceptionable-enunciating the one phenomena which is common to all living beings, and excluding all inert bodies. Here we have, in my view, the first elementary basis of true biological philosophy.........

"An organism and a suitable medium or environment. It is from the reciprocal action of these two elements that all vital phenomena proceed—not only the animal, but also the organic."

Dr. Bridges remarks on Comte's definition, in his "Evolution and Positivism": "I believe Comte to have been the first thinker who seized, amid all the manifold phenomena of living bodies, the one fundamental fact, that life consisted

in the constant action and re-action, tending to adjustment, between organism and environment (conciliation permanente entre la spontanéité interieure et les fatalités exterieures)."

Comte's definition of life, summed up in the words, "an organism and a suitable medium or environment," has been appropriated by Mr. Herbert Spencer without acknowledgment. He has used many other ideas of Comte's in the same way. He has also criticised Comte's definition. With reference to Mr. H. Spencer's criticisms on Comte's definition of life, Dr. Bridges says: "Mr. H. Spencer, in vol. i., p. 76, of his 'Biology,' throwing doubt on the initiative of Comte in this matter, represents him as speaking of this harmony between the organism and the milieu or environment, simply as one among the conditions essential to life. But Comte's words are, even in the passage quoted by Mr. Spencer, la condition fundamentale de la vie' (Philosophic Positive,' vol. iii., p. 289, 1st edition). Only a few lines before, Comte had been criticising Bichat's definition of life (the antagonism of the organism and its surroundings), on the precise ground that it suppressed 'l'un des deux élémens, inséparables dont l'harmonie constitue nécessairement l'idée générale de vie.' But these words are not quoted by Mr. Spencer. In page 301 Comte specially explains the meaning attached to the word milieu as including, not merely the circumambient fluid, but l'ensemble total des circonstances extérieures, d'un genre quelconque, nécessaires à l'existence de chaque organisme déterminé.

"The criticisms of Mr. Herbert Spencer and others on this point fail of their mark, from entirely misapprehending the purpose which the classification of animals, or, indeed, of anything else, was intended to serve. Classification, Comte considered, was made for man, and not man for classification. The scale or hierarchy of living beings is no expression of objective reality; it is a powerful logical instrument for explaining the structure of the more complex beings, by examining analogous beings or structures that are less complex. And as the mind is so constructed that the act of comparison involves the presentation in sequence, and not simultaneously, of the things to be compared, classification is necessarily, in the last resort, linear. Comte was as well aware as his critics of the necessity of the preliminary process of arranging groups according to natural affinities, without regard to linear sequence.

"The notion of the gradual Transmutation of Species, by

a passage from the simpler to the more complex, is, of course, as Mr. Darwin has taken such care to explain, very much older than his book. It was worked out with extreme care by Lamarck at the beginning of the century. (The three principles worked out with such vigour and mastery of detail by Lamarck in his Philosophie Zoologique were-(1), that organic structures increase with use, and diminish by disuse; (2), that changes in the environment lead to the increased use of certain structures, the diminished use of others; (3), that the resultant modifications become fixed in the organism by heredity.) But in England the strength of theological prejudices was too great, till the century was half over, to admit of its being popularly canvassed. The consequence is that the name of Darwin has been commonly attached to a conception which does not in reality belong to it. The specialty of Mr. Darwin was in suggesting, not the fact that species were transformed, but the particular way in which the transformation has taken place-namely, by the competition of crowded generations for subsistence, and the survival of the varieties best adapted to the environment." (Dr. Bridges, "Evolution and Positivism.")

Bichat defined man's life as twofold-first, organic; and second, animal. The organic life is continuous, while the animal life is intermittent. (The organic life in man is represented by the life of the heart, lungs, stomach, and intestines; while the animal life is represented by the life of the brain and the muscular and nervous systems. The visceral functions are continuous, while the muscular and nervous are intermittent-have, that is, their periods of activity and rest.)

Mr. G. H. Lewes says on this point: "Comparison is however, the great art of Biology, and Comte is right in devoting to it the great space he does. Instinctively, men avail themselves of this fertile source of knowledge; but so little philosophic conviction is there of its paramount importance that not one physiologist in a hundred conceives himself to be violating scientific method in beginning and ending his studies with the physiology of man! To begin the story of Euclid at the twelfth book would not be more absurd. Our ascent must be gradual. Taking a broad survey of all its manifestations, we find that Life has two grand divisions, vegetable and animal; or, to use Bichat's language, Organic and Relative life. We see plants