150 



STUDIES IN GENEEAL PHYSIOLOGY 



The three 



study of the illustrations shows that the number of new 

 tentacles corresponds to the size of the incision, and increases 

 or decreases as the length of the incision increases or 

 decreases. 



4. I cut rectangular pieces from the wall of Cerianthus 

 by cutting off the head and the foot trans- 



rversely, and dividing the resulting hollow 

 cylinder by a longitudinal cut. These 

 rectangular pieces formed tentacles upon 

 only one of the four cut edges. This 

 was upon that edge which was originally 

 directed toward the oral pole of the 

 animal. If abed, Fig. 30, represents 

 such a piece, the new tentacles sprang 

 only from the edge ab. 

 remaining sides remained 

 absolutely free from all 

 evidences of new tentacles. 

 Thus far this experi- 

 ment corresponds in behavior with that of an 

 analogous experiment upon Hydra. 1 But 

 while the piece removed from Hydra forms a 

 new cylinder, and a closed body-cavity before 

 the new tentacles sprout, 2 the tentacles upon 

 the pieces of Cerianthus are formed without a 

 new body-cavity originating, and even while 

 the entoderm is still exposed. The cut edges 

 that are free from tentacles may never heal 

 together, and a new body-cavity may never 

 be formed. In Fig. 31 is given a picture of a fragment of 

 Cerianthus bearing large tentacles while the body- cavity is 

 still open and the entoderm still exposed. The cut edges 

 show inversions and puckerings, to which I shall return 



iSeelsCHiKAWA, Zeitschrift fUr wissenchaftliche Zoologie, Vol. XLIX, p. 441. 

 2 NUSSBAUM, ArchivfUr mikroskopische Anatomic, Vol. XXIX. 



FIG. 30 



FIG. 31 



FIG. 32 



