ANGIOSPERMS 



235 



140. The gametophytes. The gametophytes of Angio- 

 sperms are even more reduced than those of Gymnosperms 

 ( 124). In order to see them, special preparations for the 

 microscope are necessary, but with the help of illustrations 

 some idea of them may be obtained. By the pollen grain 

 (microspore) three cells are formed, and two of them are 

 male cells or sperms; these three cells represent the male 

 gametophyte (Fig. 225). 

 Within the large spore 

 (megaspore), which is 

 retained in the ovule, 

 seven cells usually ap- 

 pear; and one of these 

 is an egg, no archego- 



FIG. 225. Pollen grain containing 

 a three -celled male gameto- 

 phyte; one cell represented by 

 its nucleus, the two other cells 

 being male cells. 



FIG. 226. The female gametophyte of a lily 

 before fertilization, within the old mega- 

 spore wall eight cells or their nuclei appear- 

 ing, one of which is an egg (e) ; the pollen 

 tube enters through the micropyle (m). 



nium to contain it being formed. These seven cells repre- 

 sent the female gametophyte before fertilization (Fig. 226). 

 The sperms produced by the pollen must reach the egg 

 within the ovule. The stamens that produce the pollen 

 may be in the same flower as the pistil that contains the 

 ovules with their eggs, or they may be in another flower 

 on the same plant, or they may be borne by an entirely 

 different plant. In any event, the first thing done is to 

 transfer the pollen to the pistil. This transfer, that is, 



