39+ C. M. Child 



rapidity with which the intestine is emptied of its contents in con- 

 sequence of the demand for nutritive material. Therefore intes- 

 tinal degeneration increases in rapidity with decreasing length of 

 the pieces, as is the case in the headless pieces. 



According to this interpretation the increasing rapidity of degen- 

 eration with decreasing length is due in headless pieces primarih' 

 to decreasing movement of the intestinal contents in consequence 

 of decreasing muscular activity, while in pieces with heads it is due 

 primarily to decreasing quantity of intestinal contents in conse- 

 quence of the great demand for nutritive material. In the headless 

 pieces nutritive material arising from the degeneration of the intes- 

 tinal branches accumulates in the remaining portions of the intes- 

 tine, but the branches disappear in spite of its presence. In the 

 pieces with heads, on the other hand, this material is used up 

 almost as rapidly as it is formed and the branches disappear 

 because the intestine is nearly empty. In the first case the degen- 

 eration is apparently due largely to lack of movement of the intes- 

 tinal contents, in the other to lack of intestinal contents to be 

 moved. 



Thus the data concerning the rapidity of intestinal degeneration 

 serve still further to support and confirm the conclusion that intes- 

 tinal regulation in this species is in large part a functional regula- 

 tion in response to mechanical stimuli. 



VI CONCLUSION AND SUMMARY 



The phenomena of intestinal regulation certainly afford strong 

 support to a dynamic or functional hypothesis of regulation and in 

 this respect are in accord with various other phenomena in this and 

 other species, which I have described and discussed in previous 

 papers. The intestine retains its typical form, or returns to it, 

 only when dynamic conditions are, or become similar to those 

 which give rise to the typical form. Extensive intestinal regulation 

 may occur in the absence of other form-regulation, or intestinal 

 regulation may fail to occur, while other parts undergo more or less 

 complete regulation. The results in each case are correlated with 

 the dynamic conditions in the intestine, particularly the mechani- 



