456 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



be experimentally introduced also from the outside. In all the cases discussed 

 we notice the relative preponderance of the character of the substratum over 

 the environmental factors. Nevertheless, in the course of investigation, it has 

 been found in many cases that what had hitherto been assumed to be deter- 

 mined solely by conditions inherent in the substratum, is determined in part 

 also by environmental factors, the latter thus growing in importance. The 

 further extension of the conscious control of life processes depends on the 

 discovery of additional extrinsic factors influencing tissue reactions, and the 

 possibility of modifying these experimentally. 



