178 THE BOTTOM OF THE SEA. 



This is but one example of the fate common to 

 great discoveries. At first, people are astonished by 

 them, and receive them incredulously ; afterwards, as 

 facts accumulate, it seems as if each experimenter had 

 either made the discovery for himself, or very nearly 

 approached it. If the reader has followed, even in a 

 general sort of way, the scientific movement, he will 

 be able to recall in illustration of this fact the new 

 ideas introduced into meteorology by the learned 

 physician, M. Marie Davy ; how doubtfully his first 

 communications upon the general cause of storms 

 was received, how people hesitated in the very pre- 

 sence of the facts by which the exactness of his obser- 

 vations was verified, and how the merit due to the 

 first observer has finally been acknowledged. 



Let us return to Trembley's hydra. Its body is 

 soft, and consists of one long pouch with a single 

 opening. The pouch is surrounded with tentacles, 

 which in the species we are describing are six in 

 number. On the walls of the membranous sac which 

 constitutes the animal, the buds or eggs develope 

 themselves. The latter, having arrived at a certain 

 size, leave their first home and float freely in the 

 water. The buds can either separate themselves from 

 the mother hydra, or remain fixed to her ; in the latter 

 case the same foot or stalk bears two hydras, the 

 one of which is, so to speak, grafted upon the other. 



