FORM-REGULATIONS IN CERIANTHUS. 2/3 



in a single piece than do the marginal tentacles the very slight 

 difference is not important. 



Aborally the amount of regeneration was much greater in the 

 smaller pieces 54/4 than in the larger 55^ in consequence of the 

 difference in position or level of these ends with respect to the 

 animal from which they were taken (Child, '03^). Considering 

 the relative amount of regeneration in the two pieces we find 

 that it is much greater in the smaller pieces. But the important 

 point for present purposes is the absence of proportionality. 



Another series, Series 46, affords similar results. In this series 

 disc and oesophageal region were removed from twelve large 

 specimens by a transverse cut just aboral to the cesophagus. 

 Four of the pieces (Ser. 46^) were kept without further opera- 

 tion, four others were cut in half and the distal half used (Ser. 

 46/>) and from the oral ends of the remaining four small cylin- 

 drical pieces about 5 mm. in length were cut (Ser. 46 7). Thus 

 three sets of pieces were obtained all with oral ends representing 

 approximately the same level of the original specimens. The 

 pieces A were about four fifths of the total length of the body, 

 the pieces B about two fifths, and the pieces C about one fifteenth 

 or less. During the earlier stages of regeneration there was no 

 appreciable difference in the rate or amount of regeneration in 

 the three sets except as regards two pieces of C which broke up 

 into smaller pieces and did not regenerate at all, a common 

 phenomenon in pieces near the lower limit of size. Five weeks 

 later when regeneration was complete the marginal tentacles of 

 the pieces A were 78 mm. in length, those of B 6 mm. and 

 those of C 4-5 mm. The differences in the labial tentacles were 

 similar. While the length of the tentacles in the smaller pieces 

 is not as great absolutely as in the larger it is relatively much 

 greater. The pieces C were only about one twelfth the length 

 of the pieces A but they regenerated tentacles more than half as 

 long. Moreover, if we compare these pieces with the entire 

 animals in which the marginal tentacles vary in length from 25 

 35 mm. we find that pieces one fifteenth of the size of an entire 

 animal and taken from a region some distance from the oral end, 

 /. e., from a region where the power of regeneration is less than 

 at the oral end, regenerate tentacles one seventh of the maximum 



