3 76 REPROD UCT1ON. PART n. 



perfectly similar to its parent, like that produced by a 

 bud and cutting of a tree, or the axillary fruit buds of 

 the Begonia. The leaves of that flowering plant, as 

 well as those of the Achimenes and Gloxinia, possess 

 the property of reproducing the parent plant, for, when 

 laid on moist earth and slit in different places, a young 

 plant rises from the upper side of the fracture, and 

 roots shoot down from the under. Although this manner 

 of growth resembles the germination of the embryo of 

 an archegonium, it is widely different, for the embry- 

 onic cell is fertilized by the spermatozoids, so there is 

 a certain analogy but not the smallest affinity. The 

 highest vegetable classes can reproduce the mother 

 plant in many ways, but they have nothing akin to the 

 alternation of generations exhibited by many of the 

 lower tribes, nor yet to conjugation like the Desmidiacese 

 and Diatoms. Possibly the spores resulting from these 

 two modes of reproduction, as well as the resting spores, 

 may produce new species ; certainly those resulting from 

 fructification do occasionally yield new varieties. 



Many spores produce the plant directly, others indi- 

 rectly, as most of the fungi ; but if the definition of a 

 perfect plant be that which bears the fructification, the 

 mycelium of a mushroom constitutes the plant, for the 

 mushroom itself is only a kind of sporangium or spore- 

 case. Nevertheless, the spores of the Puccinia and 

 other microscopic fungi, which are the cause of the rust 

 and mildew in wheat, give rise to a kind of prothallus, 

 c a slight fore-shadowing ' of the prothallus of the 

 Marchantia and Mosses, which only produce sporangia, 

 and those of the Perns, Horsetails, and Club Mosses, 

 whose archegonia contain the embryo of the plant it- 

 self. The fructification of the Lycopods is the highest 

 of which the Cryptogamia are capable, and brings them 

 ' into a singular analogy with the flowering class. For 

 in the ovule, or seed-vessel of the flower-bearing race, 



