Studies on Regulation. 519 



eyes are present, and the intestinal branches scarcely enter it. 

 The margin of the new part is similar to the margins of the ad- 

 joining old portions but no special differentiation of any kind can 

 be observed. It is probable that the small portions of the cephalic 

 ganglia remaining after section have undergone degeneration. 

 No further advance in regeneration occurred even after months. 



No less striking than the difference in regenerative power be- 

 tween the eight pieces containing half or more of the ganglionic 

 substance and the one piece containing only a small part is the 

 difference in their behavior. The eight pieces behaved through- 

 out essentially like normal animals. I thought I could distinguish 

 a slight difference between them and uninjured specimens as 

 regards rapidity and precision in locomotion, which might be 

 expected from the absence of the chief tactile organ, the margin 

 of the head, but the remaining parts of the head and the new 

 tissue as soon as it became functional were even more active 

 than these parts in uninjured animals; in the absence of the usual 

 tactile and other stimuli from the anterior regions of the head the 

 parts present were used all the more. The ninth piece, however, 

 resembled in behavior a piece without cephalic ganglia. It was 

 able to advance only slowly, did not adhere closely to the sub- 

 stratum, the muscular movements were irregular and ineffective, 

 and when turned upon its back the piece regained the normal 

 position only after some time and many ineffective muscular 

 contractions of various parts. The continual muscular play of 

 the lateral margins of the head was almost wholly absent in this 

 piece. In all probability the piece was practically without ganglia 

 in consequence of the degeneration of the small portions of the 

 ganglia remaining after section. 



There can be little doubt that in this piece the region of the 

 cut surface is subjected to conditions differing widely from those 

 present in the other eight. In the first place all conditions con- 

 nected with the normal rapid progression are absent; the contacts 

 with the substratum are much less close; owing to the lack of 

 coordination and reactive power the conditions resulting from mus- 

 cular movements of the head region are to a large extent absent; 

 peristaltic and other muscular contractions of the whole body 



