THE LOWER FORMS OP LIFE. 



71 



seen in the figure when the creature is hungry. Should any small 

 worm or animalcule come into contact with the tentacles as shown 

 in Fig. 92, it is immediately benumbed by the thread-like organs 

 before alluded to, which pierce the body of the victim. When seen 

 through the microscope the tentacles are found to be studded with 

 nodular protuberances, as shown in Fig. 94 (p. 72). If one of these 

 nodules is more closely examined it has the form shown in Fig. 95 



Fig. 88. The common Hydra viridis, or short-armed Hydra, with young budding from the 



parent body. 

 Fig. 89. The brown or long-armed Hydra (Hydra fusca), with young budding out from the 



bodies of mother and daughters. The long tentacles spread out in the act of seeking for 



prey (Carpenter). 

 Fig. 90. Hydra floating through the water ; &, its sucker extremity, which, having become 



dry, serves as a float. 

 Fig. 91. The same digesting. 



Fig. 92. Hydra fusca, with a small worm and animalcule just caught in the tentacles. 

 Fig. 93. Hydras ' progressing." 



(p. 72) ; and if the thread-cell is treated with acetic acid it immediately 

 shoots out, with the action of a spring, a long sharp-pointed thread, 

 as seen in Fig. 96 (p. 72). By this means the prey is slain, and 

 it is then drawn up to the mouth by the tentacles, and gradually 



