33 6 BOTANY OF THE LIVING PLANT 



haploid ; the latter results from fertilisation, and is diploid. 

 Between these, and derived respectively from them, are two phases 

 of cellular amplification, each forming a soma, or plant-body. The 

 one is the Sporophyte, or rooted plant, which springs from the Zygote, 

 and is diploid ; the other is rudimentary in the Flowering Plants, 

 though it is more fully represented in lower forms. It is initiated 

 by the haploid spore, and is itself haploid. It consists here of only 

 a few cells contained on the one hand in the embryo-sac, on the 

 other in the pollen-grain and tube. It is called the Gametophyte. 

 These two phases together constitute the alternating Cycle of Life 

 of the Flowering Plant, which thus shows vestigial relics of an 

 Alternation of Generations. 



This succession of events may often be obscured by vegetative 

 propagation, by means of buds originated in various ways. But, as 

 shown in Chapter XIII., this is a mere process of extension, or repeti- 

 tion of the individual sporophyte. It appears as though it extended 

 the cycle, but it does not really introduce any new feature. It may 



£ Sporophyte. 



*5P0R0PHYT£, 



Iegaspomnciun. * Embayo 



MlCMSPORANGIUM f ^ im 



Microspore. Megaspore. 



Fig. 258. 



be fitly represented as a supplementary cycle outside the main 

 diagram (Fig. 257). 



The doubling of part of the main cycle indicates sex-differentiation, 

 the male and female developments running parallel. This is a feature 

 which is very prominent in Flowering Plants, and for them the cycle 

 is thus doubled for about three-quarters of its extent It will be found 

 on applying a similar method successively to plants lower in the scale 

 that in them the sexual differentiation becomes progressively a less 

 marked feature. But meanwhile it is important to note that the 

 extent of this differentiation is not itself constant in Flowering Plants. 

 In certain plants the flowers are hermaphrodite, as in the Buttercup. 

 The diagram as in Fig. 257 applies to such cases. The sex- differentia- 

 tion appears in them only on formation of the pollen-sacs and ovules, 

 which are in the same flower. But in others the plant is itself either 

 male or female, and the species dioecious, as in the Willow. This 



