A PRELIMINARY EXPERIMENTAL ANALYSIS 59 



ism, represented by the inherited factors transmitted to it by its 

 parents, is by itself insufficient to account for development. 



Development is always the product of an interaction between a 

 specific protoplasm and hereditary outfit on the one hand, and 

 a particular complex of environmental factors on the other. The 

 environmental factors operative with regard to any part of the 

 organism are partly those of the external world, partly those of 

 the internal environment provided by the rest of the organism. 



