Reproduction in Relation to Agriculture 223 



Bureau of A griculture, P. I. 



FIG. 139. Five varieties of lima beans, all grown in the same soil. The differences 

 are due to differences in the plants. 



Two kinds of variations. When a crop plant like corn is 

 grown in rich soil and in poor soil, there are great differences 

 in the size of the plants and in the yield per acre. These 

 variations in size and yield are due to the environment. Even 

 though the seed planted in each kind of soil is exactly the 

 same, there will be a wide difference in the plants. 



On the other hand, there are variations that are due to in- 

 nate differences in the plants themselves. If dwarf sweet 

 corn and large field corn be planted in the same soil and 

 given the same treatment in every way, they will still be very 

 different. It is a natural quality of sweet corn, as compared 

 with field corn, to produce a smaller stalk and to have more 

 sugar in the grain; and these differences will appear even 

 when the environments are the same. We have, therefore, 



