160 THE HISTORY OF CREATION. 
conditions of life. The external influences of the latter are 
communicated to the individual parts of the body by the 
molecular processes of nutrition. In every act of Adaptation 
the individual molecular motion of the protoplasm, peculiar 
to each part, disturbs and modifies the whole individual, or 
part of it, by mechanical, physical, or chemical influences. 
The innate, inherited vital actions of the protoplasm—that is, 
the molecular phenomena of motion of the smallest albu- 
minous particles—are therefore more or less modified by it. 
The phenomenon of Adaptation, or transmutation, depends. 
therefore upon the material influence which the organism 
experiences from its surroundings, or its conditions of 
existence; while the transmission by Inheritance is due 
to the partial identity of the producing and produced 
organism. These are the real, simple, mechanical founda- 
tions of the artificial process of breeding. 
Now Darwin asked himself, Does there exist a similar 
process of selection in nature, and are there forces in nature 
which take the place of man’s activity in artificial selection ? 
Ts there a natural tendency among wild animals and plants 
which acts selectingly, in a similar manner to the artificial 
selection practised by the designing will of man?’ All 
here depended upon the discovery of such a relation, and 
Darwin succeeded in this so satisfactorily, that we con- 
sider his theory of selection completely sufficient to 
explain, mechanically, the origin of the wild species of : 
animals and plants. That relation which in free 
nature influences the forms of animals and plants, by 
selecting and transforming them, is called by Darwin 
the “ Struggle for Existence.” 
The “Struggle for Existence” has rapidly become a 
