330 Life and Immortality. 
In animals possessed of a nervous system, contractions 
only follow stimuli, which are carried to the contractile ele- 
ments by nervous threads, the internal energy representing 
the external stimulus being called nervous energy or neu- 
rism. But where a nervous system does not exist, as is the 
case in some low animals and in all plants, external stimuli 
must be justly supposed to be converted into the same form 
of energy, which in such organisms has a general circulation 
throughout the contractile protoplasm. The attainment of 
some position, favorable for the procurement of relief from 
some unpleasant sensation, or the acquisition of some agree- 
able one, or for both, is the important thing directly sub- 
served by such movements in the generality of animals. 
While we have the best of reasons for believing this to be 
true in the vast majority of animals, because fundamentally 
their structure is similar to our own, yet the inference that 
the same is true of the lowest forms of life is justifiable until 
it is proved to be mistaken. 
Whatever be the nature of any movement, whether the 
projecting of portions of its own body-substance as pseudo- 
podia in the primitive animal, the movement of flagella or 
cilia in more specialized forms, or the turning of the radicle 
of a plant-seedling in overcoming some obstacle, there is no 
resisting the conclusion that the functions of these organs, 
when once called into existence, are due to stimuli not unlike 
those which affect the motions of the limbs of the higher 
animals, and that the preliminary to all such movements, 
which are not automatic, is an effort. And as no adaptive 
movement is automatic the first time it is performed, effort, 
therefore, may be regarded as the immediate source of all 
movement. Now, effort is a conscious state, and implies a 
sense of resistance to be overcome. But when an act is per- 
formed without effort, resistance has been overcome, and the 
mechanism requisite for its performance has been completed. 
Automatism has now been reached. New movements, in 
their incipiency, necessarily meet with resistance. How this 
