THE PHYSIOLOGICAL BASIS OF RESTITUTION OF 



LOST PARTS 



C. M. CHILD 



Hull Zoological Laboratory, University of Chicago, Chicago, III. 



With One Figure 



In a series of "Studies on Regulation" which have appeared 

 in Roux's Archiv and the Journal of Experimental Zoology during 

 the last five years, and in certain other papers (Child 'o6a, 'o6b), 

 I have attempted to point out the essentially functional character 

 of form-regulation and have defined regulation in general as a 

 return or approach to physiological equihbrium after such equi- 

 librium has been disturbed or altered (Child 'o6a). According to 

 this idea form-regulation and functional regulation are both essen- 

 tially the same thing. It is perhaps unnecessary to state again here 

 what I have repeatedly stated, viz: that the term "functional" 

 is used in this connection in its widest sense as equivalent with 

 "dynamic" or "physiological" and so includes all dynamic fac- 

 tors in organic life. In otherwords,the problem of form-regulation 

 is a physiological problem and not a problem sui generis as Driesch 

 and various other authors have maintained. 



Let us consider for a moment what these assertions imply as 

 regards the factors concerned in the determination of any par- 

 ticular structure. If we assert that a given structure is altered or 

 determined by functional conditions does not this assertion neces- 

 sarily involve the idea of relation to its environment, intra-organic 

 or extra-organic or both .' As a matter of fact the very essence 

 of the term "functional" as employed in these papers is to be 

 found in the interrelation or correlation between the different parts 

 of the organism and between the organism and its extra-organic 

 environment. 



The Journal of Experimental Zoology, vol. v, no. 4 



