176 INDIVIDUALITY IN ORGANISMS 



a specialized and more effective modification of the 

 dominance which is the foundation of organic unity and 

 order. 



Moreover, the nervous system dominates or controls 

 the chemical activities of the organism to a very con- 

 siderable degree. If the primary dominance is purely 

 a matter of chemical correlation, it is difficult to con- 

 ceive how the functional dominance of the nervous 

 system has come about, but if the primary dominance 

 depends upon transmission of the same general char- 

 acter as nervous transmission, the functional dominance 

 of the nervous system is the natural and necessary 

 consequence of the primary relations. 



As regards the role of the nervous system in develop- 

 ment and reconstitution, there has been much differ- 

 ence of opinion. Many biologists have maintained 

 that the nervous system exerts a specific formative 

 influence on various parts and so determines their 

 course of development and differentiation, while others 

 deny the existence of any such influence. In the case 

 of certain organs and parts, e.g., striated muscle, it has 

 been definitely demonstrated that embryonic develop- 

 ment may occur without nervous connection, but in 

 the mature condition frequent nervous stimulation is 

 necessary for maintenance of structure and function. 

 And as regards reconstitution, some investigators have 

 found that certain parts, such as the amphibian leg, 

 regenerate incompletely or not at all in the absence of 

 nerves, while others have maintained that connection 

 with nerves is unnecessary for complete regeneration 

 of these parts. These apparently contradictory and 

 confusing results can, I believe, be very simply inter- 



