10 ELEMENTS OF AGRICULTURE 



dred miles south. Much of the seed corn for northeastern 

 United States is grown in Illinois and Iowa, but it does 

 not always mature to the proper stage for making silage. 



It is sometimes good farm management to obtain 

 seed from a climate where more vigorous seed is produced, 

 or where it can be grown at less cost; but for most of our 

 farm crops it is better to have the seed grown in the region 

 where it is to be planted. If not so grown, it is usually 

 advisable to secure it from a region that has a similar 

 climate. 



13. Artificial Selection. For centuries, man has been 

 saving the best plants and animals. In this way, the 

 changes have been much more rapid than they would have 

 been if natural selection had acted alone. Corn and wheat 

 are so changed from the original forms that there is a 

 question as to what the original forms were. Probably 

 the Indians had been selecting corn for centuries before 

 Columbus discovered America. 



Artificial selection has often developed varieties that 

 could not persist under natural conditions. We desire 

 apples with much pulp and few seeds. Natural selection 

 produced apples with little pulp and many seeds. In the 

 time of Pliny, apples were so sour that he said they 

 would turn the edge of a knife. Sour apples seem to 

 have been best able to persist under natural conditions. 



In other cases, man has aided the natural develop- 

 ment. The corn plant that produces few kernels, or that 

 does not mature, is discarded by the farmer. The wheat 

 that succumbs to rust is discarded. Cattle that do. not 

 thrive on the range are eliminated by the cattleman. 



Only within the last century has the improvement 



