THE DESCENT OF THE POLLEN-TUBE 101 



by the penetration of the loose celkihir tissue oi tlie stigma, then of tlie 

 style, by the pollen-tube. Nourishment for its growth and movement 

 is afforded partly by the contents of the pollen-mass and partly by 

 absorption from the tissues of the stigma and style with which it is in 

 contact. This process is known as the Descent of the Pollen-tube, and 

 by it the male cell or antherozoid is brought into the ovarian cavity and 

 into the immediate presence of the ovule. It then finds the foramen 

 of the latter, contact and fusion of the male cell with the oosphere is 

 effected, and fertihzation is accomplished. 



Among cryptogams, there are no such speciallj' adapted sites pro- 

 vided upon the plant-body of the parent for the germination of spores, 

 which reproduce upon any appropriate soil. They may be of two 

 sexes, the macrosjiore resulting in a gametophyte which produces 

 female cells, the microspore in one which produces antherozoids, or the 

 one gametophyte may produce both organs. In either case, the anthero- 

 zoids commonly tray el to reach the female cell. Fertilization occurs 

 very much as in phanerogarns, but no seed is produced, as will shortly 

 be explained, the embryo proceeding at once to grow and reproduce a 

 sporophyte. 



