76 VIGNETTES FROM INVISIBLE LIFE. 



benumbing others, rendering them helpless victims, 

 to be devoured at leisure. The Hydra is a voracious 

 being, and attacks and devours creatures much larger 

 and more highly organised than itself, such as small 

 crustaceans, &c. The so-called water-flea is stunned 

 by a gentle tap on its head with one of the Hydra's 

 arms, and then drawn gently to the mouth and 

 absorbed. After a while, however, the shell of the 

 Entromostracan will be thrust out, sometimes in a 

 perfect condition, the contents having been beauti- 

 fully cleared out without any injury to the exterior. 

 Small worms which live in water are a favourite 

 dish, with which the Hydra will gorge itself when 

 it gets the chance, so much so as to disfigure its 

 entire body with them. One celebrated observer 

 of the Hydra, M. Trembley, relates a contest 

 which he saw between two Hydras for the posses- 

 sion of a worm, and how it ended by one Hydra 

 swallowing the other and the worm together, and 

 having absorbed the worm in its digestive cavity, 

 quietly yielded up uninjured his troublesome but 

 weaker brother Hydra. If, however, the Hydra is a 

 good eater, it appears also to be a good faster, and 

 seems capable of existing for days and weeks to- 



