We note, in the first place, that a strict law connects the amount of conscious perception with theSo we must start from the idea that perception means eventual action,—indeterminate action. intensity of action at the disposal of the living being. If our hypothesis is well founded, this perception appears at the precise moment when a stimulation received by matter is not prolonged into a necessary action. In the case of a rudimentary organism, it is true that immediate contact with the object which interests it is necessary to produce the stimulation, and that reaction can then hardly be delayed. Thus, in the lower organisms, touch is active and passive at one and the same time, enabling them to recognize their prey and seize it, to feel a danger and make the effort to avoid it. The various prolongations of the protozoa, the ambulacra of the echinodermata, are organs of movement as well as of tactile perception; the stinging apparatus of the coelenterata is an instrument of perception as well as a means of defence. In a word, the more immediate the reaction is compelled to be, the more must perception resemble a mere contact; and the complete process of perception and of reaction can then hardly be distinguished from a mechanical impulsion followed by a necessary movement. But in the measure that the reaction becomes more uncertain, and allows more room for suspense, does the distance increase at which the animal is sensible of the action of that which interests it. By sight, by hearing, it enters into relation with an
