ZEA 171 



destroyed by this. However, pollen does not remain viable 

 much longer than twenty-four hours after shedding. 



Corn "silks" are long and plumose. The first silks to 

 appear on the ear are those from grains shghtly above the 

 base. Generally, four or five days intervene between the 

 appearance of lowest and uppermost silks. Hence, it will 

 require four or five days to poUinate all the silks of an ear. 

 Unfavorable climatic conditions, such as cold, wet weather 

 or extremely hot days, may account for the incomplete 

 "filling out" of ears. 



The silks are receptive throughout their length. Best 

 results are obtained when silk receives the pollen within a 

 few days after its emergence from the husk. Silk exposed 

 by splitting down the husks proved receptive. Again, 

 fertihzation is not prevented when tips of silks are 

 cut off. 



Fertilization, and Development of the Grain. — Just prior 

 to fertilization, the ovary of corn is bent from the perpendic- 

 ular so that the silk, instead of pointing directly out from 

 the cob, points in a direction longitudinal to the cob. Th^ 

 ovary is on a stalk (rachilla) about 2.5 millimeters long. The 

 ovule almost fills the ovary cavity. It is attached to the 

 wall of the ovary by more than one-third its circumference. 

 The outer integument is incomplete while the inner covers 

 the entire ovule, except the micropyle. This opening is just 

 above the point of attachment of the lemma. 



The ovary wall at this time, that is before fertilization, 

 possesses the following coats: 



1. Single row of epidermal cells. 



2. Many layers of parenchyma tissue, varying somewhat in 

 size. 



3. Single layer of inner epidermal cells. 



True records the presence of a pit "a short distance from 



