that the anatomical elements of the brain last indefinitely, and that they continue as they are, without renewal from birth to death. The permanence of the consciousness, be it said in passing, is connected by them with the permanence of the cerebral element (Marinesco). Thus destruction is very restricted. There is only a very slight disassimilation of the living matter, properly so-called, in the course of the vital functional activity. We may even go farther than this experimental fact. This is what Le Dantec has done when he claims that there is even an assimilation, an increase of the protoplasm. Strictly speaking, this is possible, but there is no certain proof of it; and in any case we cannot agree with him when he affirms that the increase is the _direct result_ of the functional activity and blends with it in one single, unique operation. We must, on the contrary, agree with Claude Bernard that it is only a _consequence_ of it, that it is produced in consequence of the existence of a bond of correlation between organic destruction and assimilating synthesis. Why is there this bond? That is easily understood if we reflect that the assimilating synthesis, an operation of endothermic, chemical complexity, naturally requires an exothermic counterpart, the organic destruction which will set free this necessary energy. _Formative Assimilation of Reserve-stuff. Formative Assimilation of Protoplasm._—It follows that there are in nutritive assimilation itself two distinct acts. The one consisting of the manufacture of reserve-stuff is the more obvious but the less specific; the other, really essential, is assimilation properly so-called, the reconstitution of the protoplasm. The former is indispensable to the production of the most prominent acts of vitality—movement, secretion, production of heat. If it is suspended, functional activity is arrested. We get _apparent death_, or _latent life_. But if the real assimilation is arrested, we have _real death_. According to this there would be a fundamental distinction between real and apparent death. The former would be characterized by an _arrest of the protoplasmic assimilation_ which is externally indicated by no sign. On the other hand, apparent death would be characterized by _the arrest of the formation and destruction of reserve-stuff_. It would be externally manifested by two signs:—The suppression of material exchanges with the medium (respiration, alimentation) and the suppression of the functional acts (production of movement, of heat, of electricity, of glandular excretion).