Responsiveness 65 



is not the first form of activity. Movement 

 precedes the structure which makes sensation 

 possible. When an efferent nerve carries a 

 current from the surface of the body to a ner- 

 vous centre and then a return current passing 

 over an efferent nerve causes bodily move- 

 ments, we have the simplest form of reaction 

 between organisms and the environment, but 

 nevertheless it may not be the simplest form 

 of mental activity. If, instead of starting from 

 nerve centres, a start is made from the princi- 

 ples of cell growth, a different aspect of simple 

 conditions is attained, for life may be unicellu- 

 lar in which no nervous response is possible. 

 After multicellular organisms appear it is some 

 time before a distinct nervous system arises. 

 The simple in mental life must therefore lie in 

 cell structure, and not in the more developed 

 reactions which the nervous arc permits. 



It is a well-established fact that the highest 

 form of cell is the original germ cell from 

 which all others are derived. In it are all 

 the qualities which the later-developed cells 

 reproduce, each in its own realm. The respon- 

 siveness of this germ cell to general stimuli 



