CHAPTER II 

 THE IMPROVEMENT OF PLANTS AND ANIMALS 



6. Variation in Plants and Animals. No two persons 

 are alike, nor are any two living things alike, be they plants 

 or animals. Two corn plants grown side by side are dif- 

 ferent in innumerable ways. They differ in height, in 

 diameter, in size of leaves, amount of roots, size of ears, 

 number of kernels, size and shape of kernels, size of em- 

 bryo, chemical composition of kernels, etc. In fact, they 

 differ in every characteristic that can be named. No two 

 cows are alike. They differ in color, size, shape, milk- 

 production, disposition. Some cows produce milk with 

 2 per cent of fat, and others as high as 8 per cent. Some 

 can produce three times as much butter-fat as others from 

 the same feed. No matter on what basis we make the 

 comparison, we shall always find differences. (See Figs. 1, 

 3, 11.) 



7. Law of Variation. Tne heights of many men of the 

 same race and country were arranged in order by Gal- 

 ton. Fig. 4 represents a line drawn over the heads of a 

 thousand men when thus arranged in order of height. 

 From this arrangement he found: 



(1) That the middle man represents the average height 

 of all the men. 



(2) That the line drawn over their heads was nearly 

 horizontal, except at the ends. 



(3) That near the upper and lower ends the changes 



(5) 



