6 Comparative Physiology and Psychology. | January, 
podia, and with the cohesion of its mass flowing its granules into 
the pseudopodium most attracted, and thus drawing it bodily in 
the line of the resultant of all its external and internal forces. 
The multiplicity of the components of the resultants are evident 
upon watching it. 
However highly differentiated the desires of man may be, and 
however he may fail to recognize the attraction of his own cells 
for pabulum, as soon as the food is placed within reach of the 
enteric cells, her affinities are not masked. If a complex organic 
protoplasm has the capacity of chemical conversion and union 
with oxygen and other molecules, and at the same time the union 
of oxygen with hydrogen under the proper circumstances is 
through such conditions which favor the mutual attraction at a 
distance, we cannot avoid the idea that a similar effect is pro- 
duced upon the bioplasm, and that affinity for its food is a chem- 
ical energy which is one of the forces forming, with other modes 
of motion or attraction, a resultant, each of these attracting in- 
versely as the square of its distance, and directly as its mass. 
Because the protozoon does not go straight toward its food, it is 
thought not to be attracted by it, but when in contact the pseudo- 
podia envelop it, then it is said to be a will effort. When in con- 
tact then the assimilation is possible and chemical energy asserts 
itself as a larger component of the general forces which make 
resultant motions, when at a distance the food becomes one 
_ among many influences upon its movements. 
Prehension, which is here evidently locomotory, is for the obtain- 
ing of food, and is caused by a number of natural extrinsic forces or 
attractions combined with a lesser number of intrinsic forces or attrac- 
tions. 
Chemical affinity is the prime cause of assimilation. Locomo- 
tion is evidently here only a form of the latter, due to the former 
as a direct cause, not accidentally aided, often interfered with, by 
other similar natural forces, inasmuch as the Amceba may be 
drawn away from his food unless it be near enough, or there be 
a compensatingly large enough amount to draw it against oppos- 
ing attractions. 
Throughout animal life to the highest with the development 
of food-procuring faculties this rule still holds good. The 
more the faculties increase the more direct is the food acquisition 
and the less do generally cooperate, but in this regard interfering 
Po SRS ORO SE Cee ce a eT a ERS SI ees Nig RS OS Ey ae deen 
