Fig. 51. -Hydra. 



A, A neniatocysl contained in its cnidoblast {cnb), showing the coiled 

 filament and the cnidocil {cue). 



B, The same after extrusion of the thread, showing the larger and 

 smaller barbs at the base of the thread, mm, the nucleus of the 

 cnidoblast. 



c, A cnidoblast, with its contained nematocyst, connected with one 

 of the processes of a nerve-cell («». c). 

 (After Schneider. ) 



