2QO C. M. CHILD. 



plants and in the simpler animals, in determining the character 

 of the machine and its activity, but this fact does not essentially 

 alter the case. 



Viewed from this standpoint, development, from its earliest 

 stages on, is just as strictly a functional process as functional 

 differentiation or functional hypertrophy in the stricter sense. 

 This view does not necessitate the assumption of any special 

 formative factors different in character from functional processes 

 as the factors behind or underlying development. The forma- 

 tive factors of each stage are the functional activities of the 

 immediately preceding stage (plus external factors). The proc- 

 ess of development of the organism is not essentially different 

 from the process of maintenance after development. Indeed 

 strictly speaking, development ceases only when death occurs. 

 The germ cell is an organism possessing a certain structure and 

 function, and this forms the starting point. The functional acti- 

 vity in this structure determines the next stage of development, 

 i. e., a change in structure and therefore a change in function. 

 This process continues and at the same time gradually approaches 

 a condition of physiological equilibrium. 



This view of development is of course no more an " explana- 

 tion " than is the assumption of an entelechy or that of determi- 

 nants. As a point of view, however, and as a basis for attacking 

 the problem of morphogenesis it possesses a certain value in that 

 it does away with various assumptions and places the problem 

 of morphogenesis on a strictly physiological basis. To say that 

 all organic form and structure are functional in their origin is 

 merely to say that the problem of morphogenesis is a physio- 

 logical problem and nothing more. 



This is the position which I have held since the beginning of 

 my work on regulation. I have used the word "function " with 

 reference to any and all physiological processes and activities at 

 any and all stages of development and have repeatedly called 

 attention to this fact. 1 



1 It is somewhat surprising, therefore, to find Driesch ('05, p. 790; '07, p. 180) 

 pointing out that I have put the cart before the horse in regarding function as a de- 

 termining factor in form regulation, since, as he says, an organ develops "for func- 

 tion" and does not function until it is developed, or at least until a certain stage of 

 development has been reached. The difference between Driesch and myself on this 



