Klumenberg traced their origin in it from colourless bodies. 

 Hamaan, on the contrary, states that they migrate into it from the 

 endoderm ; but he appears to start from the point of view of their 

 algae nature, and to be like some other observers ignorant of the 

 fact that chlorophyll bodies multiply by fission. It may be added 

 that Hydra viridis is unlike Spongilla or the Fresh-water Sponge ; 

 (1) when confined in the dark it does not lose its colour, and that 

 in some green varieties green angular bodies have been found 

 similar to the colourless angular bodies of Hydra fusca which 

 is brown in colour, the lower part of the body being attenuated into 

 a kind of stalk, (2) the presence of small granular gland cells on 

 the hypostume, (3) in having vacuolated gland cells at the base of 

 the gastric cavity. 



According to Zickeli, cnidoblasts are present in the endoderm, 

 while the chlorophyll corpuscles are present chiefly in the marginal 

 part of the endoderm cells, and found plentiful in their base. These 

 corpuscles are spherical and consist of an outer envelope containing 

 the chlorophyll, usually entire but sometimes in plates, with 

 central protoplasinic contents, and therefore resemble the chloro- 

 phyll bodies of plants. 



With regard to its method of locomotion, Owen in his lectures 

 on the Comparative Anatomy of Invertebrate Animals States. 

 ■" When the Hydra would change its position, it fixes one of its 

 tentacles to some supporting surface approximate to the head ; and 

 advances by leech -like movements. It can move in water as well 

 as on a plane, for it would swim, suspended to the surface of the 

 water by the foot, which is then exposed to the air ; this disc then 

 dies, acts as a float and the Hydra can row itself along by one of 

 its tentacles. Its ordinary position is one of rest." 



Trembley formerly asserted that the animal could be inverted so 

 that the ciliated epithelinum and hepatic cells were developed on 

 what was the outer-surface of the thread — other ectodermal cells 

 on what was the gastric surface, and by this means digestion would 

 be effected as well on the outer as on the inner surface, and the 

 animal continue to live. This view has however been disproved by 

 modern researches. 



The Hydra is mostly celebrated for its marvellous powers of 

 reproduction. This is in the ordinary way achieved by germination 

 or budding from any part of the body except the tentacles. 

 Sometimes two or three are proceeding at one time from the same 

 individual. A little tubercle rises en the body of the parent, which 

 enlarges every hour, and ultimately tentacles appear at the apex, 

 but no sooner are the young thus furnished than they commence 

 catching prey on their own account whilst still attached to the 

 body of their mother, but the bud ultimately constrict at its base, 

 •separates becomes an independent animal. The rate of budding 



