THE FOOD QUESTION 



careful inspection shows that he holds sev- 

 eral long, fine fish-lines at the end of each 

 of his arms, these lines terminating in a 

 little round poison sack surmounted by a 

 perfect barb, thus, j Swimming actively 

 about are many little white crustaceans 

 called daphnes, wholly unmindful of the 

 hydra, when suddenly one of them is seen 

 to swim no longer. Watching this now 

 motionless daphne, it is found that one 

 of the fatal barbs has struck him and that 

 he is motionless because paralyzed by the 

 poison from that little sack. Then the 

 hydra pulls the crustacean in as a fisher- 

 man would a trout he had hooked, and 

 soon the hydra eats him up. Now those 

 living cells in our blood called the white 

 corpuscles are capable of throwing out 

 what are termed their pseudopodia: these 

 have been seen to seize invading bacteria 

 and to draw them in to be devoured and 

 digested by the white cell. This phenom- 

 127, 



