DKVELOPHENT. 43 



closely resemble. In due course, however, one end of the germ 

 begins to contract, and gradually is developed into a sucker-like 

 base, whereupon each of the little creatures attaches itself to 

 some fixed object, and becomes for a while settled and stationary. 



And now a new character is assumed. The cilia, no longer 

 needed, disappear. A cavity is formed at the upper extremity 

 of the body, and, gradually deepening and enlarging, it becomes 

 at length a capacious mouth ; around this four arms sprout forth, 

 which being soon succeeded by four more, and these by another 

 four, we have at length from the egg of a Jelly-fish an animal, 

 which is to all appearance an ordinary hydra-form Polyp ! 



Nor is it in form alone that the correspondence holds : the 

 disguised Jelly-fish actively discharges all the functions of Polyp 

 life, twirling its arms about to entrap prey, gorging the prey it 

 secures, and ejecting the indigestible parts of its foed through the 

 mouth, precisely as is done by the Hydra itself. It has, more- 

 over, all the Hydra's power of renewing lost parts, and repro- 

 ducing the entire body from a single portion ; and, lastly, it 

 multiplies itself, as do the true Polyps, by buds or gemmules, KO 

 as often to produce a whole colony of similar beings ; add to all 

 which, that the creature has been known to remain in the 

 Polyp state for nearly two years, and no one can wonder that it 

 should often have been mistaken for an animal in its mature 

 form, without the remotest suspicion of its true character. 



After the lapse of a considerable interval, however, important 

 changes take place, and the extraordinary nature of the seeming 

 Polyp gradually becomes apparent. The body lengthens ; its 

 skin begins to shrivel ; ring-like depressions appear around it ; 

 and in a little while the entire Polyp seems as if cut into a 

 number of horizontal sections or slices, which turn up at the 

 ed;j.es, and present the appearance of a pile of watch-glasses 

 standing one within the other. Tentacles now grow out from 

 each of the upturned edges, and the several sections become 

 less and less firmly attached to each other. In one or two days 

 more, the connection between the different sections altogether 

 ceases, and one by one, beginning at the top, they swim off, and 

 become a brood of young Jelly-fish ! 



It is upon these remarkable facts, and others of a like cha- 

 racter, observed in the reproduction of some of the compound 

 zoophytes, that Steenstrup, a Danish naturalist, has founded his 



