52 



COUN CHOPS 



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44. Fertilization. — For fer- 

 tilization to take place, every 

 silk must receive at least one 

 pollen-grain, and fertilization 

 is probably surer if it receives 

 several. As the pollen is dis- 

 tributed by wind, it must be 

 very abundant to insure pol- 

 lination ; therefore, ten to 

 twenty thousand pollen grains 

 are produced to every ovary, 

 or embryonic kernel. 



The exposed end of the silk, 

 or style, is covered with fine 

 hairs and is also adhesive, so 

 that pollen-grains readily ad- 

 here when they come in con- 

 tact. It is not necessary for 

 the pollen to fall on a particu- 

 lar part of the silk ; it may 

 reach any of the exposed sur- 

 face. In fact, fertilization has 

 been accomplished bj^ placing 

 the pollen on the silk within 

 the husk. 



Soon after a pollen-grain 

 falls on a receptive silk it 

 sends out a tube, or filament, 



.-1^ ^^ 



Fig. 21. — Ear of corn showing zone 

 poorly fertilized. The ear silks in 

 successive zones from near the butt 

 toward the tip. Some unfavorable 

 condition happened when this zone 

 was in silk. 



