5' 1 8 C. M. Child. 



Fig. 7 shows the contracted condition of the cut surface after 

 section, the contraction being much more marked than in Fig. 2. 

 Fig. 8 shows the condition six days after section; new tissue is 

 growing out and the concavity of the cut surface is already 

 decreasing. Fig. 9 represents a stage fourteen days after section; 

 the new tissue is acquiring the characteristic rounded outhne 

 of the head and the cephaHc ganglia are regenerating. In 

 Fig. 10, eighteen days after section, regeneration is essentially 

 complete. The new tissue has attained about the same form 

 as the part removed, though it is not actually as large, the 

 whole body having decreased in size in the absence of food. The 

 concavity of the cut surface is nearly obliterated and the anterior 

 intestinal branches — not shown in the figures — are distributed 

 in the characteristic manner throughout the new tissue. Eyes 

 have appeared in the new tissue and the cephalic ganglia are 

 apparently fully regenerated. The piece in which the cut passed 

 near the middle of the ganglia differs from the other seven only 

 as regards the ganglia, which are somewhat smaller than in the 

 other pieces. 



In the ninth piece, however, in which only a small part of the 

 ganglionic tissue remained, the results were very different. Figs. 

 11-13 represent the various stages. After the contraction follow- 

 ing section (Fig. 11) it was not possible to distinguish with 

 certainty the remaining portions of the cephalic ganglia though 

 the piece possessed some eyes. In Fig. 12 the condition of this 

 piece six days after section is shown. It will be observed 

 that the concavity of the cut surface has increased instead of 

 diminishing as in the other cases. New tissue has filled the 

 angle between the two sides of the cut surface but does not extend 

 beyond it. The eyes have apparently degenerated, none being 

 found at this stage. No evidence of regeneration of the cephalic 

 ganglia is visible. From this condition the piece gradually 

 changed to the condition represented in Fig. 13 eighteen days 

 after section. Here the contraction of the cut surface has pro- 

 ceeded still farther and the small amount of new tissue has 

 apparently been pushed out from between the two approaching 

 surfaces. The new tissue does not form a head, no ganglia or 



