The Angiosperms 151 



of the gymnosperms. In the latter the resemblance 



of the sporophylls to the spore-bearing leaves of 



A * P 



FIG. 16 



A Diagram of simple pistil of an Angiosperm, composed 

 of a single carpel or sporophyll. The upper part forms the 

 "stigma," or receptive surface, upon which the pollen-spores, 

 sp, germinate. The pollen tubes traverse the elongated 

 " style," before they reach the ovule, or megasporangium, 

 within the enlarged cavity, or " ovary," formed by the base of 

 the carpel. Within the ovule is born a single large spore (m), 

 the " embryo-sac." 



B Ripe poilen-spore, showing large sterile cell, and anther- 

 idial cell, an. 



C The megaspore, or embryo-sac, shown in A, m, with the 

 enclosed gametophyte reduced to eight cells. At the upper 

 end, the egg-apparatus consisting of two synergidse, s, and the 

 egg-cell, o ; at the base three " antipodal " cells, a ; in the mid- 

 dle the two " polar " nuclei, p. 



the pteridophytes is very plain. In the angio- 

 sperms the sporophylls are very much more altered. 



