RADIATES. 347 



602. The Hydra is nothing but a stomach with tenta- 

 cles attached to it. It can be turned inside out like a 

 glove, and fare as well as before, showing that there is 

 little, if any difference between what may be called its 

 skin and its inside lining. Trembley, the first discoverer 

 of the Hydra?, once witnessed a very singular circum- 

 stance : " Two Polypes had seized upon the same animal ; 

 both had partially succeeded in swallowing it ; when the 

 largest put an end to the dispute by swallowing its op- 

 ponent, as well as the subject of contention. Trembley 

 naturally regarded so tragical a termination of the affray 

 as the end of the swallowed Polype's existence ; but he 

 was mistaken ; for, after the devourer and his captive 

 had digested the prey between them, the latter was re- 

 gurgitated, safe and sound, and apparently no worse for 

 the imprisonment." 



603. Hydras are produced in two ways. One is by 

 seeds or eggs. These are thrown out by the animal in 

 the autumn in the form of gelatinous globules, and in the 

 following spring Hydras come from them, and, fastening 

 themselves to some stick or other solid substance, begin 

 their quiet but predaceous life. Another mode of pro- 

 duction is by buds, thus allying these animals in a marked 

 manner to plants. Buds at first appear as slight projec- 

 tions from the outer surface of the body, and these grad- 

 ually become perfect animals, at length separating from 

 the parent to attach themselves to some solid body. The 

 stomach of the young Polype communicates with that of 

 the parent so long as they are connected together ; and 

 yet it is not uncommon to see both struggling for the 

 same worm, and gorging opposite ends of it. Sometimes 

 the young Hydra has buds start out from its body before 

 it has separated from the parent, so that we have three 

 generations in one group. This production of different 

 generations is so rapid in some cases, that it is calculated 

 that above a million descendants come from one animal 

 in a month. 



