Sensation 87 



complex system of nerves and the concen- 

 trated control of higher organisms. New nu- 

 trition having augmented the number of folds, 

 and forced the increased complexity of the 

 organism, now raises the level of its psychic 

 life. 



These changes are associated with use when 

 use is spoken of as the cause of development. 

 Judged by effects, there is a measure of truth 

 in the claim, but it should be remembered 

 that the organism is altered and new organs or 

 parts are created, not because they are of use, 

 but as a result of the way new nutrition acts 

 on the organism. The law is an expression of 

 growth and not of survival. When, however, an 

 organ is formed or a part is modified, the organ- 

 ism is out of harmony with its old environment 

 and must seek another where its new powers are 

 of use. When a new equilibrium is attained, 

 the harmony between the organism and the en- 

 vironment indicates that the environment was 

 the cause of the now useful organs. But this 

 is not true, for, as we have seen, they are the 

 result of the surplus energy of a preceding 

 environment which so interrupted the harmony 



