22 THE HAMILTON ASSOCIATION. 
causes, but rather proceed from the unceasing development of 
a single principle, we are yet at liberty to ask the evolutionist 
why and by what processes these lower forms develop into 
higher. In answer to this question, the biologist will postu- 
late two great principles which are supposed to underlie all 
development—those of habit and adaptation. 
In the law of habit, the evolutionist postulates that an 
organism possesses a tendency to continue with increasing 
ease and readiness processes and movements beneficial to itself. 
The features of habit, therefore are these—the organism receiv- 
ing astimulation from without tends to respond thereto. In this 
response there moreover arises a certain attitude or readiness 
for a similar stimulation. ‘The law of habit, however, cannot 
in itself account for organic development, since its application 
would necessarily tend to fixity and a beating of time on the 
part of the organism. Hence habit is complemented by 
another principle known as the law of adaptation or accommo- 
dation. 
The law of adaptation affirms that the organism while 
taking its habitual attitude towards repeating stimuli also 
possesses the power of adapting itself to the varying conditions 
of these stimuli. Thus, while the organism becomes habituated 
to its environment, in so far as that environment is a changing 
one, habit itself will be modified by the law of accommodation. 
Thus there will necessarily arise a constant action and 
reaction between habit and accommodation, through the 
application of which organic development may be effected. 
Thus far the claims of evolution seem in no way incon- 
sistent with the facts of development and growth as observed in 
the phenomena of biology. All organisms are found to take this 
two-fold aspect toward stimulations—while they are attracted 
toward some they recede from others. Granting all this, how- 
ever, there remains another question to be answered. Grant- 
ing that the creature answers to its stimulations in such a way 
as to increase its vitality, the question remains to be answered, 
‘“ Why does the individual respond in such a way as to produce 
such aresult?’’ ‘To answer this evolution postulates a new 
