104 ANIMAL PHYSIOLOGY. [LESSON 30. 



dies, stung to death, paralyzed. It is then seized by the terminal 

 portion of the tentacle, and conveyed to the mouth, while the other 

 tentacles are incessantly in search of food, to supply the wants of an 

 ever hungry stomach. This organ occupies the whole interior of the 

 body there is no intestine ; the terminal portion of the body forms 

 a narrow base, provided with a suctorial disc, for the purpose of at- 

 taching itself to aquatic vegetation. 



516. The simplicity of structure of these creatures may be in- 

 ferred from the fact, that they may be turned inside out without the 

 slightest detriment ; that which was the external surface instantly 

 assumes the function of a true digestive stomach, while the stomach 

 takes upon itself the office of a secreting organ, and produces young. 



517. The mode of reproduction of the Hydrse is curious : a num- 

 ber of little bud-like processes make their appearance on the external 

 surface, which soon resemble the parent in all their external charac- 

 ters ; each possesses its mouth and tentacles, and although remaining 

 attached to the body of the parent, proceeds to provide for its own 



wants. It is true that a canal 

 of communication exists between 

 the parent and the young bud, 

 through which nutriment passes 

 to help sustain it ; but after a 

 short time this canal closes up, 

 and the young continue attached, 

 or not, at their pleasure. A 

 figure is given of a family group, 

 such as those persons who have 

 kept, and bred these animals, 

 will immediately recognize (Fig. 

 178). The first figure (177) rep- 

 resents two perfect generations ; 

 the parent Polype (a), a young 

 bud (b), and a more advanced 

 one (c). 



This figure (178) shows three 

 generations ; the original parent 

 (a), the first family (6, 6), and 

 nydra viridis. "^ the second family, produced from 



the first (c, c). 



But apart from the process of budding (gemmation), there is 

 another mode by which they can be produced in great quantity, 



