MORPHOLOGY 



The subsequent development of the gametophyte occurs after the 

 pollen grain has reached the pollen chamber. In this position the tube 

 begins to develop and to penetrate the tissue of the nucellus, the tube 

 nucleus passing into it. Then the generative cell, remaining within the 



Figs. 457, 458. — Development of the embryo of Zamia: 457, the stage of free 

 nuclear division; 458, tissue-formation at base of egg, with numerous free nuclei remain- 

 ing in the general cytoplasm. — After COULTER and CHAMBERLAIN. 



grain, divides into the stalk cell and the body cell (fig. 451). The stalk 

 cell is sterile and produces nothing ; but the body cell enlarges (fig. 452), 

 and there appear within it, near the nucleus, two remarkable bodies, 

 the blepharoplasts. The body cell then divides to form the two sperm 

 mother cells (fig. 453), in each of which is one of the blepharoplasts. In 



