FORM REGULATION IN CERIANTHUS. 3 I 7 



Examination of the data shows that at all stages except the 

 final A is more advanced in regeneration than C, and C more ad- 

 vanced than D. 



It will be noted also that the regenerated parts of piece A did 

 not increase in size after 3 1 days, with the exception of the labial 

 tentacles which showed a slight increase between 31 and 43 days. 

 In the piece C a slight increase in the length of all tentacles oc- 

 curred between 3 1 and 43 days. In the piece D, however, 

 there was a marked growth during this time. In other words 

 the piece A completed its regeneration first, then the piece C, 

 and last of all the piece D. 



Throughout this series then there is a distinct relation between 

 the rapidity of regeneration and the position of the pieces in the 

 parent-body, the rapidity of regeneration decreasing with increas- 

 ing distance from the oral end. 



One other point requires consideration : the regenerated tenta- 

 cles of the piece D finally attain the same length as those of piece 

 A. This would appear at first glance to contradict the results 

 obtained from other series of experiments where not only the 

 rapidity but the amount of regeneration diminishes toward the 

 aboral end. Comparing A and C, two pieces about equal in size, 

 we find that the amount of oral regeneration in A is greater than 

 in C, as might be expected from comparison with other series, 

 since C represents a region farther from the oral end of the 

 parent-body than A. The piece D, still nearer the aboral end 

 of the parent-body, but much longer than A and C, while regen- 

 erating more slowly than either of these finally equals A in the 

 amount of regeneration. Apparently in this case the influence 

 of size has counterbalanced the influence of position. If piece 

 D was of the same size as A and C the amount of oral regenera- 

 tion would undoubtedly be less than in those pieces, but since it 

 is much larger, i. e., contains much more available material, re- 

 generation continues for a somewhat longer time (note the in- 

 crease in size of tentacles in D between 3 1 and 43 days) and the 

 regenerated organs finally, though after a longer time, reach a 

 condition similar to that in A. In this case, as in Series 54 and 

 55, the influence of size is slight and appears only in the latest 

 stages of regeneration. 



