CHAPTER ELEVENTH. 



PECULIAR MODES OF REPRODUCTION. 

 SECTION I. 



GEMMIPAKOTJS AXD FISSIPAKOUS EEPKODUCTIO^. 



510. WE have shown, in the preceding chapter, that ovula- 

 tion, and the development of embryos from eggs is common to 

 all classes of animals, and must be considered as the great 

 process for the reproduction of species. Two other modes 

 of propagation, applying, however, to only a limited number 

 of animals, remain to be mentioned, namely, gemmiparous 

 reproduction, or multiplication by means of buds, and fissi- 

 parous reproduction, or propagation by division, and also some 

 still more extraordinary modifications yet involved in much 

 obscurity. 



511. Reproduction by buds occurs among polyps, medusae, 

 and some infusoria. On the stalk, or even on the body of 



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the Hydra (fig. 170), and of many infusoria (fig. 356), there 

 are formed buds, like those of plants. On 

 close examination they are found to contain Fig. 356. 



young animals, at first very imperfectly 

 formed, and communicating at the base with 

 the parent body, from which they derive 

 their nourishment. By degrees the animal 

 is developed ; in most cases the tube by 

 which it is connected with the parent 

 withers away, and the animal is thus de- 

 tached, and becomes independent. Others 

 remain through life united to the parent 

 stalk, and in this respect present a more striking analogy to 

 the buds of plants ; but in polyps, as in trees, budding is 

 only an accessary mode of reproduction, which presupposes 

 a trunk already existing, originally the product of ovulation. 

 512. Reproduction by division, or fissiparous reproduc- 



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