2)8 C. M. Child. 



and can serve only to delay the advance of biology. Exact experi- 

 mental data concerning the physiology of development constitute 

 the most effective weapons for combating and overcoming errors 

 of this kind. Within the last few years they have been forced 

 repeatedly to retire from one defense to another. 



But there is evident in much of the work of recent years upon 

 developmental physiology a certain inclination to regard the 

 problems of morphogenesis as at present insoluble. This mani- 

 fests itself in Driesch's later work in the form of a vitalistic or 

 "autonomistic" hypothesis based on certain phenomena of 

 form-regulation, another interesting though perhaps logical conse- 

 quence of the separation of morphology and physiology. As I 

 have shown in several papers (Child, '02, '03, '04a, '04b) certain 

 of the phenomena of regulation which appear so mysterious to 

 Driesch and others are so only because they are wrongly inter- 

 preted. Others, like Morgan, who are less extreme hold that 

 while the problem of morphogenesis is fundamentally a physico- 

 chemical problem yet it is at present and perhaps will always be 

 insoluble. 



These views undoubtedly take their origin from the morpho- 

 logical conception of life, the belief that the essential feature of 

 organic development is the production of structure. When we 

 cease to consider "the tendency to return to normal proportions," 

 "form-entelechies" and other similar and fundamentally mor- 

 phological abstractions, and regard the organism as a complex 

 functioning in a characteristic manner morphogenesis appears as 

 one of the results of this functional activity of the complex. The 

 term function is used here to include all the activities of the organ- 

 ism, all transference and transformation of energy. Undoubtedly 

 qualitative differences must exist as a basis for complex function. 

 The point of importance is that the organism is primarily a func- 

 tional rather than a morphological complex. It is the qualities, 

 I. e., the capacities for functional activity that are transmitted from 

 individual to individual and from period to period. The form of 

 the organism is in general the result of its own activity under 

 characteristic external and internal conditions. 



Roux has recognized two stages in development, an organ- 

 forming and a functional stage. During the first period the vari- 

 ous organs develop without "functional" activity, while during 

 the second increasing "functional" activity and interdependence 



