REPRODUCTION. 593 



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 parent, and does not 

 receive the special protection of membranous 

 envelopes, containing a store of nourishment for 

 its subsequent growth. But in all the more 

 perfect structures, both of animals and vege- 

 tables, 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 takes 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 

 examples of this mode of reproduction ; the seeds 

 being formed at the under surface of the leaves, 

 apparently by a simple process of evolution ; 

 and when detached and scattered on the ground, 

 being further developed into a plant similar to 

 the parent. The Linnean class of Cryptogamia 

 includes all the plants coming under this de- 

 scription. In Animals, likewise, it is only in 

 the particular organs termed ovaries, that ova 



VOL. II. « Q 



