ZOOPHYTES. 17 



apparent difference, after the change had been effected, was 

 in the increased number of tentacula which the animal ex- 

 hibited about the mouth. The metamorphoses of which the 

 Hydra was susceptible did not, however, end here. It might 

 be turned inside out, as if it were the finger of a glove, so 

 that what was the skin would become the stomach, and what 

 had been the lining of the stomach would be converted into 

 the skin. Trembley relates the following circumstance. On 

 one occasion two Hydrae one stronger than the other had 

 seized a worm. Neither would let go its hold of the prey, 

 and each went on devouring it. At length, however, the 

 stronger Hydra made short work of it with his rival ; for he 

 not only swallowed the small worm, but his opponent also. 

 It might be supposed that this tragic occurrence put an end 

 to, at least, one of the combatants, but such was not the fact ; 

 for, after an hour or so, the smaller Hydra came forth unhurt. 

 The Hydra is perfectly naked, having no kind of shell nor 

 cover whatever, differing in this respect from the animals of 

 the next family (Tubulariadce). 



Two species of Tubularia, taken off the Irish coast, present 

 the appearance of a number of convoluted tubes, each sur- 

 mounted by a head of scarlet flowers, which the polype has 

 not the power of withdrawing into the tube. It is difficult 

 to convey an idea of the beauty of these sea-born blossoms, 

 when suddenly drawn up by the dredge from a depth of 

 several fathoms, each seeming petal indued with life, and 

 possessing a distinct power of motion. 



It has been observed* that, when those animals were kept 

 in the same water for a day or two, the heads dropped off; 

 but, if the water was then changed, new heads appeared, so 

 that a succession of heads might be produced from one stem, 

 with this difference, however, that each new head would have 

 a smaller number of tentacula than the original one. The 

 young are produced by means of germs, and as soon as they 

 are endued with life they are observed to have rudiments of 

 tentacula, but they do not use them for the purpose for which 

 they are employed by the mature animal. It is an object on 

 which a great degree of providential care is bestowed, that 

 the young of marine animals should be widely diffused through 



* By Sir J. D. Daly ell. Vide Dr. Johnston's " History of British 

 Zoophytes," from which valuable work most of our information has been 

 derived. 



