416 THE REPRODUCTIVE FUNCTIONS. 



of gemmules within the parent, channels are provided for 

 their exit: but the gemmules of the Actinia force their way 

 through the sides of the body, which readily open to give 

 them passage; after which, the lacerated part soon heals. 



In the instances which have now passed under our review, 

 the progeny is, at first, in direct communication with its pa- 

 rent, and does not receive the special protection of mem- 

 branous envelopes, containing a store of nourishment for its 

 subsequent growth. But in all the more perfect structures, 

 both of animals and vegetables, the germ is provided with 

 auxiliary coverings of this kind, the whole together com- 

 posing what is called a seed, or an ovum: the former term 

 being usually applied to vegetable, and the latter to animal 

 productions; and, in both cases, the organ which originally 

 contained them is termed the ovary. 



The formation and evolution of vegetable seeds take place, 

 not indiscriminately, at every point, as we have seen is the 

 case with simple germs, but only in particular parts of the 

 plant. The Filices, or fern tribes, may be taken as exam- 

 ples of this mode of reproduction, the seeds being formed at 

 the under surface of the leaves, apparently by a simple pro- 

 cess of evolution; and when detached and scattered on the 

 ground, being farther developed into a plant similar to the 

 parent. The Linnean class of Cryptogam.ia includes all the 

 plants coming under this description. In Animals, likewise, 

 it is only in the particular organs termed ovaries, that ova 

 are formed, and they are generally divided into compart- 

 ments, the whole being enclosed in a membranous covering, 

 bearing a great resemblance to the seed-capsules of plants. 



The propagation of living beings by means of ova or seeds, 

 is a process of a totally different class from their multipli- 

 cation by mere slips or buds; and the products of the former 



oviparous. Other species, again, imitate the hydra, in being 1 what is termed 

 gemmiparous, that is, producing gemmules (like the budding of a plant,) 

 which shoot forth from the side of the parent, and are soon provided with 

 cilia, enabling them, when separated, to provide for their own subsistence, 

 although they are of a very diminutive size when thus cast off. 



