48 INDIVIDUALITY IN ORGANISMS 



This, then, is in brief the dynamic conception of the 

 organic individual which has grown out of years of 

 experimental investigation, observation, and analysis of 

 facts already at hand. Its distinctive feature is the 

 interpretation of physiological unity and order in terms 

 of differences in rate of reaction and of transmitted 

 changes, instead of in terms of a hypothetical organiza- 

 tion and of transportation of chemical substances. Ac- 

 cording to this conception the central nervous system in 

 its relation to other parts is merely the final expression of 

 relation which is the foundation and starting-point of 

 organic individuation. This conception provides a 

 working hypothesis based on a great variety of evidence 

 and readily accessible to experimental and analytic 

 investigation, and while it is manifestly far from being 

 a complete solution of the problem of organic individual- 

 ity, I believe that it throws some Hght on various 

 characteristics of the organism the nature and sig- 

 nificance of which have heretofore remained obscure. 



It is perhaps necessary to point out that this dynamic 

 individuality is not the only kind of individuahty which 

 exists in the organic world. Physical individuals of 

 crystalline or crystalloid character, and perhaps physico- 

 chemical individuals of other sorts exist in organisms. 

 It is not with these, however, that we are concerned, but 

 with that sort of individuality which is distinctive of 

 the living organism, which determines harmonious 

 development and functional unity throughout the con- 

 tinuous dynamic change which constitutes life. Where 

 this organic individuahty makes its first appearance it 

 is impossible to say. The cell or protoplast in its 

 simplest terms usually shows some degree of such indi- 



