336 DOMESTIC ANIMALS 
man, no doubt a gradual modification in their qualities has 
taken place by which they adapted themselves better and 
better to their new mode of life. Naturally their masters 
would save the better individuals and use them for breeding 
purposes ; and, of course, when this practice is followed con- 
sistently for a period of time, it is sure to result in the gradual 
improvement of the race. It is necessary, however, that the 
selection shall be made on the same principle, uniformly and 
continuously. If a better horse is desired, it will avail very 
little to select one now for the sole reason that it is a fast 
runner, and in the next generation pay no attention to speed 
but breed from the one that is heaviest and strongest. Our 
ideal must be definite and fixed, and then we must breed 
toward that ideal, generation after generation. 
In the history of stock breeding this was not done until 
comparatively recent times, and while farm animals have 
been undergoing gradual improvement from the time they 
were domesticated, it was not until within the last century or 
so that very great progress was made in the development of 
our various specialized breeds. The results of recent improve- 
ments are almost beyond belief. For example, in 1850 the 
sheep of this country produced an average of 2.4 pounds of 
wool per fleece, but in 1900 the average yield had increased 
to 6.9 pounds. The increase per cow in butterfat in the 
same period is considered just as striking. Steers are now 
matured for the meat market in their third year instead of the 
fifth year as in 1878, so that a much larger number may be 
supplied annually to the butcher from the same number kept 
on the farm. Again, it is estimated that the ordinary farm 
horse in America is 25 per cent more efficient than it was in 
1851, when the breeding of draft horses in this country 
began. 
