Vol. VII. November, 1904. No. 6 



BIOLOGICAL BULLETIN 



FORM-REGULATION IN CERIANTHUS, VII. 

 TENTACLE-REDUCTION AND OTHER EXPERIMENTS. 



c. M. CHILD. 



EXPERIMENTS ON CERIANTHUS MEMBRANACEUS. 



In the preceding papers certain experiments upon C. incin- 

 braiiaccns have been mentioned from time to time. It was im- 

 possible on account of lack of material to make my studies of 

 this species as full and complete as those of C. solitarins. The 

 data obtained were sufficient, however, to show a close correspon- 

 dence between the two species as regards regulative phenomena. 



It was possible to delay tentacle-regeneration by preventing the 

 establishment of internal water-pressure by the methods employed 

 for C. solitaries, viz., by reopening at short intervals or by giving 

 the pieces a form such that closure was delayed or prevented. 



It is not necessary to give the data of the experiments in full 

 since they add nothing essential to the facts already given for 

 C. solitarius. A few points are, however, of some interest 

 especially in view of certain experiments which Loeb performed 

 on this species. - 



In consequence of the greater thickness and stiffness of the 

 body-wall in this species as compared with C. solitarius it is much 

 less difficult to obtain pieces in which the enteron remains more 

 or less widely open for a considerable length of time, in some 

 cases indefinitely. In such pieces tentacle- regeneration is greatly 

 delayed but sooner or later some regeneration does occur. 



Loeb ('91, pp. 44 and 45, Figs. 4-6) describes briefly and 

 figures cases of this kind which he obtained by cutting rectangular 

 pieces from one side of the body. His figures show that regen- 

 eration of the tentacles occurs but they also show that it is much 

 delayed, since in his Fig. 6, the most advanced stage shown, 



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