Studies on Regulation. 



517 



which the cut was near the posterior region of the ganglia showed 

 complete regeneration. 



The eight posterior pieces of this series corresponding to Groups 

 B and C of the anterior pieces all showed complete regeneration; 

 the ninth posterior piece corresponding to one of the two anterior 

 pieces comprising Group A regenerated only very slightly, the 

 posterior piece corresponding to the other piece of Group A was 

 lost. This comparison of the anterior and posterior pieces shows 

 very clearly that regeneration, whether posterior or anterior, 

 is most complete in these pieces which contain the largest amount 

 of ganglionic tissue. In the piece B described in the preceding 



^ 



paper posterior regeneration was qualitatively complete though 

 much less in amount than in Group A; the posterior piece corre- 

 sponding to B showed complete anterior regeneration. Thus in 

 this case the ganglionic tissue was divided so evenly that both 

 pieces retained some considerable portion of it intact. If it were 

 not for the crushing and displacing effect of the cut upon the soft 

 tissues it would doubtless be possible to cut through the ganglia 

 transversely in such manner that both posterior and anterior 

 pieces would regenerate completely. This case is, however, the 

 nearest approach to success which I have obtained in numerous 

 experiments of this kind. 



The history of the first eight pieces is illustrated by Figs. 7-10. 



