238 THE HISTORY OF CREATION. 
perceive that every apparently free action of the will is 
the result of previous ideas, which are based on notions 
inherited or otherwise acquired, and are therefore, in the 
end, dependent on the laws of Adaptation and Inheritance. 
The same also applies to the action of the will in all animals. 
As soon as their will is considered in connection with their 
mode of life, in its relation to the changes which the mode 
of life is subject to from external conditions, we are at once 
convinced that no other view is possible. Hence the changes 
of the will which follow the changes of nutrition, and 
which, in the form of practice, habit, etc., produce variations 
in structure, must be reckoned among the other material 
processes of cumulative adaptation. 
Whilst an animal’s will is adapting itself to changed 
conditions of existence by the acquisition of new habits, 
practices, etc., it not unfrequently effects the most remark- 
able transformations of the organic form. Numerous 
instances of this may be found everywhere in animal life. 
Thus, for example, many organs in domestic animals are 
suppressed, when in consequence of a changed mode of life 
they cease to act. Ducks and fowls in a wild state fly 
exceedingly well, but lose this facility more or less in a 
cultivated state. They accustom themselves to use their 
legs more than their wings, and in consequence the muscles 
and skeleton used in flying are essentially changed in their 
development and form. Darwin has proved this by a very 
careful comparative measurement and weighing of the 
respective parts of the skeleton in the different races of 
domestic ducks, which are all descended from the wild duck 
(Anas boschas). The bones of the wings in tame ducks are 
weaker, the bones of the legs, on the other hand, are more 
