J 58 KEPKODUv^TION. 



readily roproduced. Salamanders even possess ths facu'ty 

 of reproducing parts of the head, including the eye with all 

 its complicated structure. Something similar takes place in 

 our own bodies, when a new skin is formed over a wound, 

 or when a broken bone is reunited. 



332. In some of the lower animals, this power of repara- 

 tion is carried much farther, and applies to the whole body, 

 so as closely to imitate fissiparous reproduction. If an earth- 

 worm, or a fresh-water polyp, be divided into several pieces^ 

 the injury is soon repaired, each fragment speedily becoming 

 a perfect animal. Something like this reparative faculty is 

 seen in the vegetable kingdom, as well as the animal. A 

 willow branch, planted in a moist soil, throws out roots below 

 and branches above ; and thus, after a time, assumes the 

 shape of a perfect tree. 



333. These various modes of reproduction do not exclude 

 each other. All animals which propagate by gemmiparous 

 or fissiparous reproduction also lay eggs. Thus the fresh- 

 water polyps (Hydra) propagate both by eggs and by buds. 

 In Vorticella, according to Ehrenberg, all three modes are 

 found ; it is propagated by eggs, by buds, and by division. 

 Ovulation, however, is the most common mode of reproduc- 

 tion ; the other modes, and also alternate reproduction, are 

 only additional means employed by Nature to secure the per- 

 petuation of the species. 



SECTION 11. 



ALTERNATE AND EQTJIVOCAL REPRODUCTION. 



334. It is a matter of common observation, that individus's 

 of the same species have the same general appearance, by 

 which theii peculiar organization is indicated. The trans- 



