9 8 



MAIZE 



CHAP. 

 IV. 



has a peculiar, heavy, sweet, lasting odour. Pollen is essential 

 to the fertilization of the pistillate flowers and consequently to 

 the development of the grain ; without it no grain can be 

 formed. This may easily be demonstrated by tying a clean 

 paper bag tightly over a maize ear, before the silks develop, 



A B 



Fig. 44. — Effect of partial pollination. A, Pollen was applied artificially 

 after most of the silks had ceased to be receptive. B, Imperfect pollination, 

 possibly due to temporary injury to silks by insects. 



and leaving it so covered until after the silks have dried up 

 (Figs. 43 and 44). 



Pollen "dust" is composed of an enormous number of 

 roundish grains (Fig. 42). Each individual grain is a separate 

 cell, consisting of a cell-wall of usually two layers or coats, 

 surrounding a mass 1 of protoplasm ; within the cell are two 



