Studies en Regulation. 5 -5 1 



the result in this case was due to some difference in the distribu- 

 tion or arrangement of nervous structures, to exceptional vigor, or 

 to an exceptional amount of reserve energy it is impossible to 

 determine. The parallelism between motor activity and regenera- 

 tive power is also well shown in this piece. 



5. Anterior Regeneratiorj After Repeated Section. 



In his work upon Leptoplana atomata Schultz ('02) reached 

 certain conclusions widely different from my own with respect to 

 anterior regeneration, yet the results of experiments described by 

 him are essentially similar to my own as far as they go. As will 

 appear, Schultz's conclusions are probably due to the fact that his 

 experiments were confined to a particular region of the body. 

 He was never able to obtain anterior regeneration "selbst bei 

 solchen Exemplaren nicht, denen nur ein geringer vorderer Kor- 

 perabschnitt, weit vor dem Pharynx, abgeschnitten wurde." The 

 position of the cut with respect to the cephalic ganglia in such 

 cases is not stated, but there can be little doubt that it was pos- 

 terior to the ganglia. In fact, it is probable that Schultz never 

 observed anterior regeneration in the presence of the cephalic 

 ganglia. I have no doubt that if he had done so he would have 

 obtained results similar to my own and would have reached 

 entirely different conclusions regarding the absence of anterior 

 regeneration. His views on this subject are briefly stated as 

 follows: the margins of the cut come together in such manner that 

 union occurs and thus the region where regeneration would begin 

 ("Regenerationspunkt") is separated from the periphery by old 

 tissue and, moreover, the union of the muscular layers over it 

 prevents further growth. 



This attempt at a simple explanation of the absence of anterior 

 regeneration involves, I believe, a complete inversion of the actual 

 course of events. The cut edges unite because there is not suffi- 

 cient new tissue formed to prevent this union, which is probably 

 due to mechanical conditions in the tissues. It is very probable, 

 however, that after their union the outgrowth of new tissue from 

 the end cannot occur. The multiplication of parenchyma cells 

 which Schultz describes as occurring within the muscular layer 



