Vol. VII. August, 1904. No. 3 



BIOLOGICAL BULLETIN 



FORM-REGULATION IN CERIANTHUS, V. 



THE ROLE OF WATER- PRESSURE IN REGENERATION : FURTHER 



EXPERIMENTS. 



C. M. CHILD. 



REDUCTION OF WATER-PRESSURE BY MEANS OF ARTIFICIAL 

 OPENINGS AND ITS EFFECT ON REGENERATION. 



Early in the course of my experiments the apparent relation 

 between internal pressure and the rapidity of tentacle regeneration 

 was noted. The facts obtained incidentally led me to believe that 

 it would be possible to influence the course of regeneration by 

 altering the internal pressure. The results of experiments have 

 amply justified this belief, though I hope at some future time to 

 be able to apply to the problem new methods which have sug- 

 gested themselves, and thus to eliminate some of the complica- 

 ting factors. 



The problem was attacked experimentally by various methods 

 which may be grouped under two heads : one group of methods 

 consisted in the frequent reopening or spreading of the margins 

 of an artifical opening in the body-wall, the other in the attempt 

 to make an artificial opening in the body-wall of such a form that 

 complete closure and consequent distension of the piece with 

 water would be impossible or greatly delayed. The chief dif- 

 ference in the two sets of methods is that with the first, the pieces 

 are reopened at stated periods, every alternate day, every day, or 

 oftener, while with the second they remain undisturbed after sec- 

 tion. The results obtained by these two methods differ little and 

 afford strong evidence in favor of the view that water-pressure is 

 an important factor in regeneration in Ceriantlms. 



127 



