Regeneration as Functional Adjustment 425 



of regulation, Child rejects, but I think on insufficient grounds. 

 I have assumed that, according to the symbiotic relation of the 

 parts of an organism, upon removal of a part, such as A, in the 

 figure, the undifferentiated tissue in the region of ^ w'\\\ differen- 

 tiate in the direction of the missing part because of the functional 

 demands, or for what, for want of a better term, I have called social 

 pressure, upon that tissue. "This," according to Child, in refer- """ 

 ring to the particular case illustrated by the diagram, "is exactly 

 what will not occur under these conditions. If all the cells A-F 

 are symbiotically correlated then removal of one of them, y^, must 

 affect all the others, ;. e., the whole complex is altered by removal 

 of one of its members. It is perfectly clear that the 'social pres- 

 sure' of the altered complex will not be in the direction of differ- 

 entiation of the indifferent cell into something like y^ but in some 

 other direction, in other words, the indifferent cell cannot replace 

 A but will form something different. Moreover, since all the cells 

 were dependent upon A in some degree, the removal of A will 

 probably render continued existence impossible for some of them 

 and their place will be taken by the undifferentiated cells, but 

 these will also develop into something different because the 'social 

 pressure' is altered. It is perfectly evident that no regulation in 

 the sense of replacement of a missing part could occur in such a 

 complex." 



Now this conclusion may be perfectly clear to Dr. Child, but 

 I must confess — perhaps I am blinded by my bias in this matter — 

 that it is far from being so to me. According to Child, since the 

 removal of y^ would alter B, G, F, etc., not only something differ- 

 ent would be developed in place of A, but the whole complex, 

 according to my theory, would be profoundly altered. Now, I 

 admit that the removal of A tends to alter 5, G and Fy etc. How 

 far this tendency will result in a modification of these cells depends 

 on the plasticity of the organism and the degree of mutual depend- 

 ence of the parts — factors of course which vary in different organ- 

 isms. But Child overlooks the fact that according to the sym- 

 biotic relation assumed, the other cells C, D, E, etc., tend to keep 

 B, F, G in their original condition. In so far as these remain in 

 their original state, their influence on the indifferent tissues in the 



