with respect to the constituent arts of the living individual were more successful. It was not enough to know in a general way that the phenomena observed in living things are in the last resort the same in kind as those which are known as physico-chemical, and that they obey the same laws. Between the phenomena of living things and those of inanimate Nature there existed too wide a chasm; there was no way of passing, deductively, from physico-chemical laws to vital phenomena, and the scientific explanation of organic forms and of functions was of necessity defective. The author of the "Anatomie générale" simply recognized in organs various elements, which he grouped in families, with a view to define, under the general name of tissues, the basis of their structure. In these elements he recognized, independently of their physical and chemical properties, special properties which he justly denominated vital, inasmuch as it is by them that life manifests itself, and which are, properly speaking, the function of these elements. Bichat's generalizations were, doubtless, in his own mind, in opposition to the theory which refers vital phenomena to physico-chemical properties; in point of fact, they have established a relation between functional facts and the general properties of matter. The functional facts of organs are explained by the elementary properties of the tissues; and the latter, though we cannot as yet refer them to physico-chemical properties, are, nevertheless, brought into remarkably close relation with them through our modern ideas of the constitution of organic substances and the principle of the equivalence and transformation of forces.
Still, these relations could not be perceived prior to the discovery of the relations which connect organisms and their tissues with external forces possessed only of physico-chemical properties; and this conception dates from a time long after Bichat's day. We have reason for believing that the part assigned by Lamarck to the action of external circumstances upon organisms first suggested this conception, owing to one of those mysterious operations of the mind which, out of an idea vaguely descried, and even, perhaps, not accepted in the form in which it first presented itself, forms a nucleus around which experience and reasoning group proofs, and which the inventive faculty develops under the form of a doctrine apparently brand-new. The doctrine of the action of "general external modifiers," which Blainville sets forth summarily in his "Cours de Physiologie générale et comparée," by no means possessed, even in his own mind, all the importance it later assumed in science under the name of "doctrine of media," after Auguste Comte had given it so prominent a place in his "Biologie." But, by bringing upon the scene the action of external circumstances upon the sum total of a living organism, and by calling attention to the effects they produce therein, whether as stimulating or reviving the functions, or as suspending the same, Blainville prepared the way for a better interpretation of vital phenomena; and
