374 



C. M. Child 



earlier than the longer pieces. In consequence of the more rapid 

 intestinal reduction and earlier death of these short pieces lateral 

 intestinal branches never develop in the postpharyngeal region. 



These tw^o pieces represent the two extremes as regards intes- 

 tinal regulation in prepharyngeal pieces. The results in other 

 pieces fall between these two extremes and differ in detail accord- 

 ing to the part of the prepharyngeal region included in the piece. 

 In every case, however, and my observations include some fifty 

 cases, very rapid disintegration of the lateral intestinal branches 

 took place in the region posterior to the new pharynx and in the 

 larger pieces a new system ot lateral branches developed later. 



// 



12 



Figs, ii and 12 



In prepharyngeal pieces from which the head-region and the 

 cephalic ganglia have been removed the formation of a new post- 

 pharyngeal region and pharynx takes place in the same manner as 

 when the ganglia are present (Child '05c), the only difference be- 

 ing that the new postpharyngeal region is longer, the new pharynx 

 farther from the posterior end and the process of degeneration 

 somewhat less rapid than m pieces with posterior ends at the same 

 level but containing the ganglia. As was pointed out in my 

 earlier paper (Child '05c), the only ground which suggests itself 

 for this difference is the functional relation between prepharyngeal 

 and postpharyngeal regions. Removal of the ganglia reduces 

 the functional activity of the prepharyngeal region very greatly, 

 but affects the activity of the postpharyngeal region to a less extent, 

 hence in regulation the reaction to the altered conditions at the 

 posterior end involves more of the posterior region of the piece 

 than in cases where the ganglia are present, since the energy of 



