124 BOTANY. [CHAP. iv. 



oospheres, the latter after fertilization forming by cell- 

 division the embryo or young plantlet, which is for some 

 time protected and supplied with food from structures 

 belonging to the asexual phase of the parent plant, the 

 whole forming the seed. From the above it will be 

 observed that the entire bulk of every phanerogam is 

 homologous with the asexual phase of those cryptogams 

 having distinct alternation of generations. 



The advantages of the changes indicated depend on 

 the fact that in cases of cross-fertilization a greater 

 number of seeds are produced than by self- fertilized 

 plants of the same kind, and further, the seeds resulting 

 from cross-fertilization produce stronger and more 

 vigorous plants than those resulting from self-fertiliza- 

 tion ; consequently those groups of plants showing a 

 tendency to favour the sexual mode of reproduction, 

 being more robust than the other types, took possession 

 of the most favourable positions and spread at a much 

 greater rate than those cryptogams encumbered with 

 sexual and asexual phases, because the latter mode did 

 nothing towards invigorating the species, consequently 

 in phanerogams, as already stated, the presence of the 

 asexual mode of reproduction is either a remaining 

 vestige of the old idea, or its revival under conditions 

 unfavourable for the full development of the sexual 

 method of reproduction. 



The term " flowerless plants," as often applied to 

 cryptogams, is misleading, in fact, not correct ; the idea 

 of a flowering plant being one that reproduces itself 

 sexually, a condition true of the great majority of 

 cryptogams, but, as already explained, the particular 

 method by which the antherozoid or fertilizing body 



