1 88 ORGANIC EVOLUTION 



nature of the organism ; and, second, the character of the 

 environment and its relation to the organism. Of the lat- 

 ter, the character of the environment and its relation to 

 the organism through the struggle for existence and in 

 other ways, we know much. Of the intimate nature of the 

 organism, however, we as yet know but little. We do not 

 even know whether the life processes are conducted in 

 accordance with the ordinary principles of chemistry and 

 physics, or in conformity to some more subtle " vital " prin- 

 ciples. There are many questions which we are unable to 

 answer because we do not understand the intimate nature 

 of living things. Are there inherent tendencies in the or- 

 ganism, leading it to evolve in certain directions rather 

 than in others, as St. George Mivart contended, or is its 

 evolution controlled by the needs created by the character 

 of the environment? Such questions are as yet beyond 

 our ken, and we have no present prospect of soon being 

 able to answer them. It is possible that our knowledge of 

 evolution may very materially advance when our knowledge 

 of the life processes of living things becomes more intimate. 



