FORM REGULATION IN CERIANTHUS. 305 



almost continuous observation and the accompanying manipula- 

 tion necessary to examination, which is a source of irritation to 

 the regenerating pieces and may often effect the result by caus- 

 ing rupture of new tissue or other injuries. 



In general then the method pursued in the experiments was 

 that of examining at intervals pieces to be compared and noting 

 the condition of each. Owing to the number of points to be 

 observed and the necessity for indicating slight differences any 

 arrangement of the results in tables is unsatisfactory : they are 

 given, therefore, in much the same manner as first recorded. The 

 series of experiments described are selected from a large number 

 but the results were remarkably uniform in all cases. In 

 the description of the stages only the most salient features of 

 the regeneration are mentioned in most instances. In all cases, 

 however, unless definite statement is made to the contrary, regen- 

 eration proceeded in the typical manner. 



I. DESCRIPTION OF EXPERIMENTS. 



SERIES 22. ' 



September 24, 1902. The oral end, including the cesophageal 

 region, was removed from twenty-three large specimens of C. 

 solitarius and the remaining portion of the body was divided by 

 a transverse cut as nearly as possible into two equal pieces (Fig. 

 i), oral halves being designated A, aboral B. All of the pieces 

 A were placed in one aquarium, all of B in another. 



September 27 : Three days after section : 



A. Most of the pieces are still collapsed, but in a few the ends 

 are closed and a slight distension with water is evident. 



B. All still collapsed. 



September 28 : Four days after section : 



A. All the pieces are more or less distended with water : three 

 pieces show the tentacular ridge and the first traces of marginal 

 tentacles. 



B. Three pieces are closed and somewhat distended, the re- 

 mainder still collapsed. 



September 29 : Five days after section : 



1 The series retain the numbers given them in my notes. 



