Studies on Regulation. 



481 



than in Fig. 13 (Series 78, ganglia present). There is no marked 

 difference in the amount of regeneration. 



Thirty-four days after section the pieces of Series 78 have at- 

 tained the condition represented in Figs. 15 and 16, and Figs. 

 17 and 18 represent the condition of Series 79. Here, as in the 

 preceding case there is a marked difference between the two 

 series. In the series containing the cephaHc gangha, the amount 

 of regeneration is greater, the posterior portion of the new pharynx 

 has regenerated in the new tissue to a much larger extent, and 

 intestinal branches fill the new tissue much more completely. 

 Later stages afford no additional features of interest. 



J.4 



Series 80 and 81. In these two series the level from which pos- 

 terior regeneration occurred was at the posterior end of the 

 pharynx (Fig. 19). Series 80 consisted of five pieces with head 

 and cephalic ganglia intact and Series 81 of five pieces from which 

 the head and ganglia had been removed (Fig. 19). 



Figs. 20 and 21 represent the condition of Series 80 fourteen 

 days after section and Figs. 22 and 23 of Series 81 after the 

 same interval. There is little difference between the two series 

 at this stage except that in Series 80 the intestinal branches have 

 penetrated further into the new tissue. 



