:q6 



THE POPULAR SCIENCE MONTHLY 



Fig. 1. 



Types appearing in a Single Field of Maize. 

 the center has been isolated. 



A strain like the ear near 



it simply takes an alert eye for their detection, comparative tests to 

 prove their merit and the time needed to produce a sufficient increase 

 for commercial use. Some of our other important grain crops like oats 

 and rye are more often cross-pollinated, as is also our chief grass crop, 

 timothy. But as maize is probably the most difficult crop to deal with, 

 and is a typical cross-pollinated plant as well as our most important 

 cereal, perhaps it will be of interest to take a short survey of some of 

 the problems with which one has to deal when endeavoring to improve 

 it by selection. 



Maize is the only one of our cereals that is monoecious. The tassel 

 contains the pollen or male element while the silks are the stigmas of 

 the female flowers. In order that the pollination of the silks shall be 

 relatively certain, each tassel produces about thirty million pollen 

 grains ; and as the ears average less than five hundred seeds apiece, there 

 are about sixty thousand pollen grains produced for each kernel. With 

 such a large amount of superfluous pollen floating around in the air, 

 there is a great deal of inter-crossing between the neighboring plants. 

 This fact has been an obstacle to the improvement of maize, but it has 

 been offset by one advantage it possesses over the other cereals, that of 

 producing large ears. Since each individual ear must be handled and 

 its characters noted at husking time, it is not strange that ears with 

 desirable variations sufficiently striking to catch the eye of the grower 

 have become the parents of numerous distinct varieties. By selecting 

 desirable seed ears and isolating them from other varieties, various 

 strains have been produced that are remarkably uniform in characters 

 such as color that have forcibly attracted the attention of the breeder. 

 Even in these strains, however, there are many natural types growing 

 side by side and continually crossing with each other. There are stalks 



