HYDRA — ITS MULTIPLICATION BY BUDS. 459 



which communicates with the cavity of the stomach) is very- 

 remarkable, especially in the Hydra fusca ; whose arms, when 

 extended in search of prey, are not less than seven or eight 

 inches in length ; whilst they are sometimes so contracted, when 

 the stomach is filled with food, as to appear only like little 

 tubercles around its entrance. By bieans of these instruments, 

 the Hydra is enabled to derive its subsistence from animals, 

 whose activity, as compared with its own slight powers of loco- 

 motion, might have been supposed to remove them altogether 

 from its reach ; for when, in its movements through the water, 

 a minute worm or a water-flea happens to touch one of the ten- 

 tacula of the polype, spread out as these are in readiness for 

 prey, it is immediately seized by this, other arms are soon coiled 

 around it, and the unfortunate victim is speedily conveyed to the 

 stomach, within which it may frequently be seen to continue 

 moving for some little time. Soon, however, its struggles cease, 

 and its outline is obscured by a turbid film, which gradually 

 thickens, so that at last its form is wholly lost. The soft parts 

 are soon completely dissolved, and the harder indigestible por- 

 tions are rejected through the mouth. A second orifice has 

 been observed at the lower extremity of the stomach ; but this 

 would not seem to be properly regarded as anal, since it is not 

 used for the discharge of such exuviae ; it is probably rather to 

 be considered as representing, in the Hydra, the entrance to that 

 ramifying cavity, which, in the compound Hydroida, brings in^o 

 connection the lower extremities of the stomach of all the in- 

 dividual polypes (Fig. 223). A striking proof of the simplicity 

 of the structure of the Hydra, is the fact that it may be turned 

 inside out like a glove ; that which was before its external tegu- 

 ment becoming the lining of its stomach, and vice versd. 



301. The ordinary mode of multiplication in this animal, is by 

 a gemmation resembling that of Plants. Little bud-like pro- 

 cesses (Fig. 220, i, c) are developed from its external surface, 

 which are soon observed to resemble the parent in character, 

 possessing a digestive sac, mouth, and tentacula ; for a long time, 

 however, their cavity is connected with that of the parent, but at 

 last the communication is cut off by the closure of the canal of 

 the footstalk, and the young Polype quits its attachment and 

 goes in quest of its own maintenance. A second generation of 

 buds is sometimes observed on the young Polype, before quitting 

 its parent ; and as many as nineteen young Hydrse, in different 

 stages of development, have been seen <lhus connected with one 

 original stock (Fig. 221). Another very curious endowment 

 seems to depend on the same condition, — ^the extraordinary 

 power which one portion possesses of reproducing the rest. Into 

 whatever number of parts a Hydra may be divided, each may 

 retain its vitality, and give origin to a new and entire fabric ; so 

 that thirty or forty individuals may be formed by the section of 

 one. The Hydra also propagates itself, however, by a truly 



