Primitive Lasso-Throwers. 



37 



from five to eight hollow tentacles or feelers, which opens 

 into a central cavity or stomach. Firm and muscular are 

 the walls of the sac, so that the little creature, which is not 

 fixed permanently to whatever it is found clinging to, may 

 stretch itself out or draw back as its own volition dictates, 

 or move slowly along by means of its sucker, or float 

 easily or contentedly upon the water. But the most remark- 

 able, as well as the most interesting thing about this odd 

 creature is the power which it possesses of overcoming ani- 

 mals more powerful and active than itself. 



FRESH-WATER HYDRA MOORED AND SEARCHING FOR PREY. 



Groping about with its flexible arms, which are closely 

 invested with fine jelly-hairs, with which it seemingly feels, 

 or attached to some leaf or bit of floating stick, its tentacles 

 reaching out in all directions, the Hydra instantly paralyzes 

 any minute insects, young snail or infusorian that touches its 

 feelers, and complacently closing its arms over the helpless 

 victim, carefully tucks it away, so to speak, into its stomach, 

 where it is speedily digested. This power of paralyzing and 

 thus readily capturing active living creatures is due to the 



