374 ANGIOSPERMS 



Under favourable circumstances the seed germinates. 

 By absorption of moisture its contents swell and burst the 

 seed-coat, and the root of the phyllula (r) emerges, followed 

 before long by the stem (st) and cotyledons (<tf). The 

 phyllula thus becomes the seedling plant, and by further 

 growth and the successive formation of new parts is converted 

 into the adult. 



In Gymnosperms we see an even more striking reduction 

 of the gamobium than in Selaginella. The female prothallus 

 is permanently inclosed in the megaspore, and the megaspore 

 in themegasporangium : the ovaries also are greatly simplified. 

 The male prothallus is represented by the smaller cell of the 

 microspore, and no formation of sperms takes place, fertiliza- 

 tion being effected by cells developed in the extremity of a 

 tubular prolongation of the larger cell of the microspore, and 

 resulting from a modification of its nucleus. 



It is worthy of notice that Phanerogams, alone among 

 the higher organisms, have abandoned the ordinary method 

 of fertilization by the conjugation of ovum and sperm. In 

 this respect they are the most specialized of living things. 



ANGIOSPERMS. 



In this group the general relations of the main parts of 

 the plant stem, leaves, roots, &c. are the same as in 

 Gymnosperms. 



The flowers, in which, as in Gymnosperms, the organs of 

 reproduction are contained, have a very characteristic struc- 

 ture, which, although presenting almost infinite variety in 

 detail, is the same in its essential features throughout the 

 group. 



A typical angiospermous flower (Fig. 89, A) is a greatly 



