378 ANGIOSPERMS LESS, xxx 



In Gymnosperms we se an even more striking reduction 

 of the gamobium than in Selaginella. The female prothallus 

 is permanently inclosed in the megaspore, and the megaspore 

 in the megasporangium : 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. 88, A) is a greatly 

 abbreviated shoot, consisting of a short axis (fl. r) of limited 

 growth bearing four whorls of leaves, of which those of the 

 two distal whorls are sporophylls. 



The axis of the floral shoot (A. fl. r) is usually broad and 

 more or less conical in form and is called the floral 'receptacle. 

 The leaves of the lower or proximal whorl (pcr^\ usually 

 from three to five in number, are small green bodies which 

 cover the other parts in the unopened flower : they are called 

 sepals and together constitute the calyx. 



