266 C. M. CHILD 



a special mechanism. To others it seems possible to account 

 for the observed facts only by the assumption of an 'entelechy' 

 or other vitalistic principle. Only here and there do we find a 

 definite and conscious attempt to show that life and regulation 

 are in large measure the same thing, that the mechanism of regu- 

 lation is the mechanism of life and that form regulation so-called 

 is merely morphogenesis occurring under certain special condi- 

 tions. 



As considered more fully in another paper, soon to appear, my 

 own position is that the problem of regulation is, at least biolog- 

 ically, the problem of life. Regulation is the process of equili- 

 bration in the system, following a change in the medium or envi- 

 ronmental conditions. Without the change in conditions which 

 within certain limits, leads to regulation, or without the power of 

 equilibration, life would sooner or later cease. On the other 

 hand, equilibration, ^. e., regulation if some sort must result from 

 changed conditions, as long as the dynamic processes are not com- 

 pletely inhibited or the system otherwise destroyed by the changes. 



From this view it follows that in the formation of a whole from 

 a part artificially isolated we are concerned with processes of 

 reproduction and development and that here as in the formation 

 of a new individual from a fertilized egg, the problem of heredity 

 is given in its essential terms. We see from experiments on 

 regulation that physical or physiological isolation of a certain 

 degree or kind is a necessary condition for the initiation of the 

 change toward wholeness in a part. Moreover, many, if not all 

 forms of reproduction in nature differ from our crude operative 

 isolations chiefly in that the isolation of the part which forms the 

 reproductive element is brought about by physiological condi- 

 tions in the organism rather than by mechanical means (Child, 

 '11a) 



In the reconstitution of the whole from a part all the essential 

 features of the reproduction of an organism of specific character 

 from a reproductive element of a certain constitution are as truly 

 present as in the development of the egg, though in different 

 form because of the difference in conditions. Whether we call 

 the process regeneration, restitution or reconstitution, whether 



