306 



C. M. CHILD. 



A. Distinct marginal tentacles are present on eight pieces ; 

 the remainder all distended and with tentacular ridge. 



B. All closed and more or less distended ; in a few distension 

 is just beginning ; none with distinct tentacles. 



September 30 : Six days after section : 



A. All with distinct marginal tentacles from 0.5 i.omm. long. 



B. The pieces which were the first to close and become dis- 



tended show traces of marginal tentacle buds; all 

 pieces distended with water. 



October I : Seven days after section: 



A. All with marginal tentacles 1.0-2.0 mm. long. 



B. Traces of marginal tentacles on all pieces 

 except those which were the last to close. 



This series was not kept under observation for 

 the later stages. As regards the earlier stages, 

 however, it shows clearly that the aboral pieces 

 regenerate somewhat less rapidly than the oral 

 pieces, although the latter are cut at both ends, 

 the former at only one end. The difference be- 

 tween the two sets of pieces is universal, not even 

 the most advanced pieces in the set B showing as 

 rapid regeneration as the least advanced of A. In 

 general the differences between pieces of the same 

 set are slight. 



SERIES 45. 



November 7, 1902. Tentacles and disc were removed from 

 four specimens and the remaining portion of the body was cut 

 into four pieces, A, B, C, D, as nearly equal as possible (Fig. 2). 

 All of the pieces A were placed in one aquarium, all of B in 

 another, etc. The pieces A contained a part of the oesophagus. 



November 9 : Two days after section : 



A. Ends closed and piece distended ; as in other similar cases 

 the cut oral margin of the oesophagus has united with the oral 

 margin of the body-wall so that the pieces possess a well- 

 developed mouth-opening. 



B, C, D. All collapsed. 



November 10 : Three days after section : 

 A. Marginal tentacular ridge appearing. 



B 



\J 



FIG. i 



