The phenomena so far studied manifest themselves in the lowest animals, in many plants, even also in the highest representatives of the animal kingdom. They cannot be related closely to nervous dif´erentation; they are, before all, reactions of the living matter, of protoplasm, to stimulating influences. The nervous system and the sensorial organs serve simply as agents to the reactions provoked by these influences ; they are not primordial factors, for one observes identical reactions in a throng of organisms in which these organs show no trace of dif´erentation. In these diverse cases the sensation, or nervous impression, must be absent or singularly reduced. The automatism seems perfect, even when it causes phenomena of periodicity which reveal an organic memory.
The preceding observations do not apply to phenomena arising from species memory. With these we leave the domain common to all organisms to enter into that of animals in which the nervous svstem plays a predominate role. Psychism appears in the form of a choice between the diverse modalities offered in response to variations of stimuli. It acts, therefore, as only a rudimentary psychism, rudimentary and very distant, limited to stimulating variations and to impressions which they have already produced in the species. In the course of ages these last have been graven on the brain, centers and have left there a permanent trace; and to-day the same variations determine the responses belonging to these old survivals. The vague psychism at the beginning has become an automatism.
Let this change from psychism into automatism hold our attention, for it is not the exclusive appanage of species memory. One sees it more and more and more plainly in the other phenomena which constitute the relative life of the higher animals. But these phenomena are complex and varied, thanks to the development of nervous and sensorial systems which permit the individual to know his surroundings better, to be more susceptible to the influence of these surroundings, and to receive livelier impressions; more apt for the same reason to be graven on his brain and to leave there a persistent trace. From that comes an individual memory, more extended and more flexible than the species memory, whose narrow domain is limited to stimulating variations.
It is the brief study of these new phenomena which will be the object of our research. Leaving behind the lower animals and protoplasmic irritability, we will confine ourselves entirely to articulate animals, to follow then the development of individual memory, and to examine the change of the manifestations of this memory into automatic acts.