FORM-REGULATION IN CERIANTHUS. 153 



3. In all pieces in which closure is delayed by any means the 

 process of regeneration resumes its typical course after closure 

 and distention are permitted to occur. 



4. It is believed that these experiments demonstrate the impor- 

 tant influence of the general internal water-pressure upon regen- 

 eration in Cerianthus. Complete elimination of internal pressure 

 was impossible with the methods employed, therefore complete 

 inhibition of regeneration cannot be expected in any case. 



5. The retardation in regeneration of the tentacles and expan- 

 sion of the disc may perhaps be due essentially to the decreased 

 force and volume of the intermesenterial circulatory currents in 

 open as compared with closed pieces. 



6. Irregularities, such as local absence of tentacles, differences 

 in time of appearance and local differences in size may be due 

 to local differences in the circulatory currents which in turn are 

 the result of local foldings, inrollings, or contractions of the 

 body-wall. 



HULL ZOOLOGICAL LABORATORY, 

 UNIVERSITY OF CHICAGO, 

 October, 1903. 



BIBLIOGRAPHY. 

 Child, C. M. 



'033 Form-Regulation in Cerianthus, I. The Typical Course of Regeneration. 

 Biol. Bull., Vol. V., No. 5, 1903. 



'oab Form- Regulation in Cerianthus, II. The Effect of Position, Size, and other 

 Factors upon Regeneration. Biol. Bull., Vol. V., No. 6; Vol. VI., No. I, 

 1903. 



'043 Form-Regulation in Cerianthus, III. The Initiation of Regeneration. 

 Biol. Bull., Vol. VI., No. 2, 1904. 



'O4b Form-Regulation in Cerianthus, IV. The Role of Water-pressure in Re- 

 generation. Biol. Bull., Vol. VI., No. 6, 1904. 



Goette, A. 



'98 Einiges uber die Entwickelung der Scyphopolypen. Zeitschr. f. wiss. Zool., 

 Bd., LXIIL, 1898. 



