ANGIOSPERMiE 181 



antlieridial cell passes into it. Either before this 

 happens, or later, the antheridial cell divides into two 

 sperm-cells, but no motile spermatozoids are formed. 



The upper part of the pistil, the stigma, is usually- 

 provided with papillae which hold the pollen, and the 

 surface is often adhesive owing to a peculiar secretion 

 which at the same time probably serves to induce the 

 germination of the pollen. In some cases there is an 

 open tube through the pistil, through which the pollen- 

 tubes grow, but more commonly the central part of the 

 style is occupied by a peculiar conducting tissue serv- 

 ing to nourish the growing pollen-tube, which grows 

 through it much as a fungus hypha grows through the 

 tissues of its host. On reaching the ovary, the pollen- 

 tube grows along the placenta or tissues from which 

 the ovules spring, until finally it reaches the micropyle, 

 or opening of the ovule, which it then enters, and pen- 

 etrates through the overlying tissues of the apex, to 

 the egg-apparatus. The expulsion of the generative 

 cell is effected much as in the Conifers, and one of the 

 sperm-nuclei makes its way into the egg-cell, the lowest 

 of the three cells of the egg-apparatus (Fig. 44, B, o), 

 the two others, the synergidse (sj/), probably assisting 

 in the transference of the male nucleus from the pollen- 

 tube to the egg. 



The effect of pollination is usually marked by a rapid 

 growth of the ovary, as well as the development of the 

 ovules into seeds. The development of the latter is 

 quite similar to that in the Gymnosperms, but the 

 further changes in the carpels, to form the " fruit," is 

 peculiar to Angiosperms. We cannot here go into 

 details as to the great variety shown in the fruits of 



