NEMATOCYSTS 



301 



A 



FIG. 77. Hydra, 



A, a nematpcyst contained in its cnidoblast (cub), 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 nematocyst, 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 



