BUDDING TENTACLES OF GONIONEMUS. 



247 



that it is at first solid, but that later " the cavity of the circular 

 canal is drawn into it." "The entodermal cells, arranged radi- 

 ally about the central axis, thicken until they are forced away 

 from the center and a tubular cavity is left." This process, he 

 states, begins at the proximal end and the cavity is gradually 

 " carried out along the axis of the tentacle toward the tip." In 

 this bud there seems to be present the cavity at the distal end so 



FIG. 8. 



that the method just mentioned does not apply, at least not 

 wholly. In Fig. 6 the cells are evidently arranging themselves 

 in rows next the supporting layer, with their edges meeting near 

 the center, suggesting a drawing away from the axis and a forma- 

 tion of a cavity (as Perkins suggests) connecting the cavity of 

 the tentacle with the cavity already formed in the bud. Fig. 9, 

 however, would seem to indicate a somewhat modified process. 

 The cell outlines are not distinct, so that their arrangement cannot 

 be definitely determined, but in the central part of the core are a 



