904 The American Naturalist. [October, 
already in contact, cannot be explainedin this way. Their selec- 
tion of food and rejection of injurious substances, though not 
always performed without errors, indicates the presence of sensa- 
tion. The building of external protecting envelopes composed 
of grains of solid substances by the Difflugiz cannot be explained 
by the action of physical causes only; and the arrangement of 
pieces in regular order as an envelope by the Rotifer Melicerta 
indicates still more definitely the presence cf consciousness in 
some form. 
We cannot discover any such design in the movements. of 
phagocytes and of spermatozooids. The former engulf leu- 
cocytes and other bodies with which they come in contact, very 
possibly for physical reasons, but do not pursue them, nor indicate 
their perception of their presence in any way. The movements 
of spermatozoöids appear to be without direction other than that 
given them by the vibrations of their flagella, by the cilia of the 
canals which they traverse, and perhaps by some physical attrac- 
tion not at present explainable. The attraction of the sperma- 
tozoöids of certain ferns and hepatica by solutions of malic acid 
and cane sugar have been regarded as chemical, but this can 
scarcely be the correct explanation. A physical relation is much. 
more probable, if sensation is excluded. 
The presence of predication cannot be inferred from the exist” 
ence of consciousness in the lowest forms of life. An action is 
designed if it is a response to a present stimulus or sensation, 
even if there be no memory, and the act is a new one 
every time the stimulus is applied. It is evident, however, that 
education commences low in the scale, since some of the acts of 
the Infusoria indicate an adaptation of means to ends which can- 
not be supposed to be possible to a totally new experience. The 
discharge of the weapon-like cilia of the Dinidium at its prey 
. would indicate that the animal knew the effect of the act from 
past experience, and anticipated that food would be secured in 
this way from its success in previous performances of the kind. 
Memory is, so far as we know, a general attribute of living pro- 
toplasm, and it is probable that it enters into the psychic acts of 
very low organisms. It may be in the beginning unconscious 
