22O 



EDMUND B. WILSON. 



a new peduncle being formed posteriorly and a new axial polyp 

 anteriorly, while neither the severed axial polyp nor the pe- 

 duncle regenerates, though both may live for a sufficient period 

 of time (in some cases a week or more). In this instance the 

 peduncle, as usual, failed to regenerate, while the middle piece 

 regenerated an axial polyp in front and peduncle behind. The 

 anterior piece (2 B] formed an exception to the rule in that it 

 regenerated a large polyp at the posterior end, a form being 

 produced with two similar polyps united at the base and point- 



A 



B 



C 



FIG. 2. A, outline of young colony with two pairs of buds, in the contracted 

 state, showing planes of section. B, the anterior piece (axial polyp), twenty-four 

 hours later ; the middle piece already showed a new axial polyp and peduncle well 

 under way. C, the anterior piece fifteen days after the operation, with new polyp at 

 base, and the original tentacles reduced. 



ing in opposite directions (Fig. 2, C). Each possessed a stomo- 

 daeum, and the mesenteries were continuous from one to the 

 other, bearing six mesenterial filaments. At one side was a 



o 



rounded elevation that may have been a regenerating peduncle ; 

 but the animal died without further change. An interesting feature 

 of this case was the degeneration of the original tentacles, which 

 lost their pinnules and became greatly shortened so as to form rudi- 

 ments closely similar to those of the regenerated polyp, or those 

 of an early larva. I have observed the same phenomenon in young 

 colonies in which the peduncle, after its removal and regenera- 

 tion, had been again successively twice removed and regenerated, 

 the whole animal having been in the meantime considerably 

 reduced in size. This shows that regeneration takes place at the 

 cost of material throughout the colony, even involving regressive 



