296 



HYDRA 



CHAl' 



Fig. 75. — Hydra. 



A, a nematocyst contained in its cnidoblast {^nb\ showing its coiled filament 

 and the cnidocil (cnc). 



B, the same after extrusion of the thread, showing the larger and smaller barbs at 

 the base of the thread ; nu. the nucleus of the cnidoblast. 



C, a cnidoblast, with its contained neraatocyst, connected with one of the processes 

 of a nerve-cell (nv. c). (From Parker's Biology : after Schneider.) 



in as a hollow pouch : the free end of the latter is continued 

 into a hollow coiled filament, and from its inner surface 



