198 C. M. CHILD. 



when the animal was distended and oriented in the characteristic 

 position with oral end uppermost than when it was strongly con- 

 tracted. In the later stages the disc did not appear at all oblique 

 except in the contracted condition. 



The rates of regeneration in the three experimental pieces were 

 slightly different owing to the delay in closing in some, but if we 

 take the most advanced of these pieces and compare it with the 

 two controls it is seen that there is a marked difference between 

 the lower portion of the disc in the experimental piece and the 

 controls B. In the controls B the tentacles were 1-1.5 mm - 

 seven days after section and must therefore have appeared on the 

 sixth day, since they were not distinct on the fifth day. In the 

 most advanced experimental piece the tentacles had not appeared 

 on the lowest portion of the disc on the tenth day after section ; 

 four days later, however, they were about 2 mm. in length and 

 must therefore have appeared about the twelfth day. There is 

 then a delay of about six days in the appearance of the marginal 

 tentacles on the lowest part of the oblique disk as compared with 

 the time of appearance of the tentacles on a transverse disc at the 

 same level of the body, and in the other experimental pieces the 

 delay is still greater. It is evident then that the retardation in 

 tentacle regeneration on the lower portion of an oblique piece is 

 much greater than the retardation due to differences of level in 

 transversely cut pieces. The data of the experiment and Figs. 

 5 and 6 show that the appearance of the labial tentacles is sim- 

 ilarly delayed. 



As regards the time of appearance of the marginal tentacles on 

 the uppermost portion of the oblique disc and on the control 

 pieces A, the fact that tentacles appeared in the most advanced 

 experimental piece in three days, while in the controls they 

 appeared somewhat later, indicates that tentacle regeneration is 

 probably slightly accelerated in the upper portion of the oblique 

 discs. According to my notes this is the only case observed in 

 all of my experiments in which tentacles appeared in three days. 

 It is barely possible that the oblique cut in this piece passed so 

 far orally that small stumps of a few tentacles remained. In view 

 of this possibility little stress can be laid on the apparent acceler- 

 ation in tentacle-regeneration in this one piece, and unfortunately 



