THE REPRODUCTIVE STRUCTURES 



107 



During this long period the pollen tube behaves like 

 a parasitic fungus, drawing food materials from the 

 nucellus, as the region- containing the pollen chamber 

 is called. As the tissues are used up the pollen chamber 

 becomes larger and larger until it finally extends entirely 

 through the nucellus, so that nothing remains between 

 the female gametophyte and the pollen tubes. The 



Fig. 54. — Stangeria paradoxa: nucellus of ovule with pollen tubes 

 with the body cell, except the lower tube, in which the body cell has 

 divided, forming the two young sperms. Highly magnified. 



appearance of the nucellus, the pollen chamber, and the 

 pollen tubes just before the sperms escape is shown in 



Fig. 55- 



Meantime the body cell undergoes a remarkable 

 development; it increases in size, and two small, spheri- 

 cal bodies, called " blepharoplasts " because they produce 

 cilia, make their appearance. Long, slender, threadlike 

 strands radiate in every direction from the blepharo- 

 plasts, which, at first scarcely visible with the best 



