ATROPHY 127 



during the closing in of the piece, the new proboscis lies not at the 

 top of the sub-umbrella space, but, as seen in the figure, quite to one 

 side. Pieces even smaller than these one-fourth jelly-fish will assume 

 the bell-like form, especially if they contain a bit of the margin of the 

 old bell and a part of one of the radial canals, as shown in Fig. 39.}, D. 

 Although I have kept these partial medusae for several weeks, and 

 have fed them during this time, I have found that the missing organs 

 do not come back. That these pieces do undergo a certain amount of 

 regeneration is shown by the formation of a new proboscis, and, in 

 certain cases, a new radial canal. Even the tentacles may be par- 

 tially regenerated, as Hargitt has shown, especially, as I have found, 

 if the margin of the bell is cut off very near the base of the line of 

 tentacles. Small knobs appear along the cut-edge, but the pieces die 

 before regeneration goes very far. If, however, the margin is cut 

 off in only one quadrant, new tentacles may be produced along the 

 cut-edge. 



