48 DOMESTICATED ANIMALS AND PLANTS 
every character that enters into the composition of individuals 
and of races. 
Thus among sweet apples some are sweeter than others within 
the same variety, and this is true quite independent of color or 
size. Of all the trotting horses in the world some can go in 2:40, 
some in 2: 30, a few in 2:20, and a very few in 2:05 or less. 
Of a thousand ears of corn taken at random from the same 
field and of the same variety, some will be short and others 
long, while the rest will stand between. This is variability in 
a single character. It is, moreover, a kind of variability that 
can be exhaustively studied by exact statistical methods, —a study 
that is strongly recommended not only for its exactness but for 
its influence in fixing definite notions of type and that devi- 
ation from type which is called variability. These methods of 
study are given in a later chapter, a careful study of which is 
strongly recommended at this point. 
Historical knowledge of original species needed. In order to 
devise practical methods of still further improving the domesti- 
cated races and more completely adapting them to the service 
of men, we need, first of all, to know everything possible of the 
character of the original species as they lived in a state of nature, 
— how they behaved toward one another and how they prospered 
before man interfered with their affairs. In other words, from the 
way of the wild we can learn substantial lessons as to methods of 
improvement, and this we propose to outline in the next chapter. 
Summary. No plant or animal has yet been brought to its highest state 
of efficiency, though some individuals are vastly superior to others, and vari- 
ability is universal. Besides this, our needs and our desires are constantly 
changing, mostly by way of advance. There is need, then, for still further 
improvement, and the best course to pursue in deciding upon methods is, 
first of all, to study species in a state of nature, where these species existed 
in the wild for many generations previous to domestication. 
Exercises. 1. The student should calculate with as much accuracy as 
possible and report upon the cost of maintaining domestic animals in his 
own neighborhood, especially as influencing the cost of meat and milk 
production. 
