Thus natural rhythms produce more or less profound periodical modifications in the organism. This periodicity leaves, in the long run, a trace in the tissues. It becomes engraved there and ends by manifesting itself aside from the causes Which have produced it. It becomes a habit, and, like all habits, presupposes a memory.
Treating of the phenomena to which he gives the very appropriate name of vital rhythms, Bohn observes that they are frequent in organisms, and that he cannot see in them any manifestation of psychism. He is right, without a doubt, for psychic manifestations presuppose a choice, at least originally, and we are here in the presence of automatic movements equally wide-spread in the two kingdoms (animals and plants) and produced by inflexible stimuli to which the organism submits like a plaything. When we consider these phenomena, adds the distinguished biologist, "we are tempted to speak of 1 memory,' but we are not exact in speaking so of vital rhythms, and simply risk arousing confusions, the word 'memory, ' in fact, being employed in very different senses. " I do not share this opinion of the original savant, to whom we owe so many interesting researches in periodicity. When the organism retains an impression, a memory of rhythmic influences to which it has been subject, one cannot deny to the manifestations of this memory the quality of phenomena of memory, and the appellation " vital rhythms," which is used to designate them, does not forcibly imply this character. This is not a futile play of words; it acts, in effect, to show a suggestion of memory under a form which may be called organic memory, because it is engraved upon the tissues, and rules, in a way, the functioning of the being. This memory has an importance which cannot be disputed. Piéron has devoted a long study to it in one of his most interesting works. Bergson 1 attributes to it the name which we have chosen, and Roubaud has applied to his blood-sucking larvae the equivalent term physiological memory.
Organic memory is the result of external stimuli like tropisms, and like them, also, it is independent of the differentiation of tissues and manifests itself by automatic acts. But it is distinguished essentially by the fact that it can provoke reactions (motor or others) without the aid of the stimuli which originated it. This is its principal character, one which marks a first tendency of the organism to liberate itself from the environment which surrounds it. With the beings which possess it, observes Bohn, "the protoplasm remembers in some sort the stimuli which have acted upon it"; it can act again without them, and by the simple effect of acquired habit. It is surely not yet psychism, but it is at least a stage on the road which leads to it.
1 H. Bergson, L'Evolution créatrice, 1907.