ANGIOSPERM 181 
antheridial 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 papille 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 (Vig. 44, B, 0), 
the two others, the synergide (sy), 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 
