PROVOCATIVE BIOLOGICAL THEORIES 77 



"In the first place, the organic individual is alive and, 

 therefore, consists of the complex substances termed in 

 general protoplasm; second, it is more or less definitely 

 limited in size ; third, it possesses a more or less definite 

 morphology, a visible form and structure, which is asso- 

 ciated in some way with dynamic and primarily chemical 

 activity ; fourth, a greater or less degree of order, coordi- 

 nation, correlation, or harmony as it is variously called, 

 is perceptible in the character of its form and structure 

 and in the dynamic activities of its constituent parts. 

 In short, the organic individual appears to be a unity of 

 some sort; its individuality consists primarily in this 

 unity, and the process of individuation is the process of 

 integration of a mere aggregation into a unity, for this 

 unity is not simply the unity of chance aggregation, but 

 one of a very particular kind and highly constant char- 

 acter for each kind of individual." 



The problem presented, then, is to try to determine 

 the nature of the unity underlying individuation, which, 

 in turn, has developed into the problem of control or regu- 

 lation of the potentialities of development; a search, it 

 might be called, for some principle of regulation in a 

 growing organism. 



The Organisationcentrum Theory. Hans Spemann 

 (1922-24) has brought forth a suggestive idea in this 

 field, which the Germans call the Organisationcentrum 

 Theory, a theory resulting from the study of early stages 

 of organic development. Spemann's experiments, cover- 



