528 CM. Child. 



cates the maximum amount of regeneration obtained in cases of 

 this kind. In most cases such pieces die within ten days after 

 section and none were kept alive more than twenty-eight days. 

 Shorter pieces cut further posteriorly do not live as long and show 

 even less regeneration than these. 



These three examples are sufficient to indicate the decrease in 

 the power of anterior regeneration with approach toward the 

 posterior end of the body. The results obtained in other series 

 were in general similar. 



As regards motor activity the differences at different levels are 

 parallel to the differences in regenerative power. The further 

 posterior the level of section the less the motor activity. Pieces 

 from widely different levels like those considered above (Fig. 27) 

 show marked differences in motor activity. The pieces of the 

 first series, which had lost only the ganglia and a short portion of 

 the cords, were almost as active as Series 71 considered in the 

 preceding section, which had lost only the ganglia; progression 

 occurred, though of course slowly, and the pieces were able to 

 adhere to the substratum in some degree and to right themselves 

 when turned over. The special activity of the anterior end, 

 present in some degree in Series 71, was not observed in these 

 pieces. The pieces with anterior ends near the middle of the 

 pharyngeal region were distinctly less active. When progression 

 occurred it was less rapid than in the first set, direct comparison 

 between pieces of the two kinds being frequently made; the pieces 

 righted themselves less readily and sometimes did not succeed at 

 all; adhesion to the substratum was very slight; and finally all 

 movements were less frequent and powerful. But the pieces 

 from the region posterior to the pharynx showed even less motor 

 activity. Very slow progression sometimes occurred in conse- 

 quence of ciliary movements, but in such cases the piece simply 

 slid along without holding to the substratum and frequently on 

 the dorsal surface. The pieces were usually incapable of righting 

 themselves. Reactions to stimuli were slight and the pieces 

 showed few traces of movement of any kind when left undisturbed. 

 In the normal animal this region of the body is the chief organ of 

 attachment during locomotion, but separated from other parts it 



