100 



C. M. CHILD. 



ally formed one side of the terminal disc being now represented 

 only by the narrow shrivelled strip separating the two discs. 

 About thirty clays after section the shrivelled portion separating 

 the two discs was ruptured by the increase in diameter of the 

 discs. Each portion of it remained attached to the disc on its 

 own side but gradually underwent atrophy. Reference to Fig. 

 6 renders it evident that this shrivelled strip was all that separ- 

 ated the two mouths : with its rupture the two mouths became 

 one. The two discs, or two parts of the disc continued to ap- 

 proach the same level, the constriction marking the region where 

 the shrivelled strip stretched across (Fig. 5) gradually disap- 

 peared and on December 12, forty-nine days after section the 



FIG. 6. 



specimen was normal in appearance, with marginal tentacles about 

 12 mm. in length and labial tentacles about 3 mm. 



The history of other specimens of the same sort corresponds 

 closely with that of the piece just described. It is possible of 

 course to modify the results in various ways : for example the 

 lateral cut may be made more or less deep and thus cause the 

 isolation of a greater or less number of iritermesenterial chambers 

 above it and consequently the retardation in regeneration and the 

 later reduction of a larger or smaller number of tentacles. It is 

 possible to make the cut so deep that only three or four tentacles 

 remain distended on the terminal disc all the rest appearing on 

 the lateral disc. On the other hand, if the cut involves only a 



