244 c - M - CHILD. 



growth resulting from an abundant food supply constitutes in any 

 case a complicating factor in the analysis of various phenomena 

 of form regulation. In such experiments as permit the taking of 

 food a complete analysis of the phenomena would include studies 

 of the effect of abundant food supply, but previous experiments 

 along this line indicate that the results in the lower animals differ 

 only in degree and not essentially in kind with the presence or 

 absence of food. 



Four species of Ccrianthus were employed for experiment, viz., 

 C. solitariits, C. membranaceus and two smaller undetermined 

 species, one of them almost completely colorless. It was soon 

 discovered, however, that C. solitarins, a very common form in 

 the Bay of Naples, was more favorable than the other forms on 

 account of size, coloration of body and abundance. My atten- 

 tion was therefore devoted chiefly to this species, though the 

 other forms, and especially C. membrdnaceus, were used for com- 

 parative study. 



THE COURSE OF REGENERATION. 



The cut pieces were isolated in dishes which were placed in 

 aquaria supplied with flowing water. During the earlier stages 

 of regeneration the pieces showed little tendency to creep out of 

 dishes, but later' it was necessary in some cases to cover the 

 dishes with netting to prevent escape. 



In Cerianthus the course of regeneration is complicated in 

 many cases by various factors, such as the form of the pieces, 

 the internal water pressure, etc. The simplest cases are those in 

 which the body is divided by a transverse cut into two pieces, or 

 a piece is removed by two transverse cuts. In such cases a 

 nearly cylindrical piece is obtained which regenerates at the cut 

 end or ends. Such pieces are best fitted for the study of 

 the "typical 1 course of regeneration at the two ends, and 

 since a knowledge of this is important as a -preliminary to the 

 study of experimental control of regeneration this paper is de- 

 voted to a description of the phenomena concerned in such 

 cases. 



A piece cut from the middle region of the body (e. g., between 

 the lines aa and bb, Fig. i) will serve as an example. 



