4 INDIVIDUALITY IN ORGANISMS 



between its parts, but such a unity may again con- 

 ceivably be the result of a pre-established harmony in 

 construction like that of a steam engine, or it may be a 

 unity which itself determines, constructs, and har- 

 monizes as a flowing t^ream sculptures its channel and 

 develops a characteristic morphological structure and 

 dynamic activity in mutual relation to each other.' 

 According to this last purely mechanistic conception the 

 problem of individuality is accessible to scientific investi- 

 gation and may be solved by scientific methods. 



While it is impossible to exclude absolutely the 

 dualistic alternative as long as a complete mechanistic 

 solution of the problem has not been reached, the 

 advance of scientific knowledge has resulted in demon- 

 strating the mechanistic character of one feature after 

 another of the organism and in narrowing the field 

 within which vitalistic assumptions are still possible. 

 We know that actual energetic relations do exist between 

 the different parts of the individual. These relations, 

 which are often called physiological correlation, are of 

 various sorts: mechanical, such as pressure or tension 

 between parts; transportative, consisting in the trans- 

 portation or exchange of substances between different 

 parts; transmissive or conductive, consisting of changes, 

 impulses, or excitations transmitted or conducted from 

 molecule to molecule or from particle to particle. Physi- 

 ological correlation of these different kinds unques- 

 tionably pla^ys a very important part in the unity of 

 the individual, and the only possible method of pro- 

 cedure to determine whether the unity consists essen- 



* Child, "The Regulatory Processes in Organisms," Jour, oj 

 Morphol., XXII, 191 1. 



