NATURAL SELECTION. 
265 
there is a constant tendency to revert to the wild 
state. This is true of many vegetables and other 
plants, too. 
Garden sweet peas have been made to bloom in 
great variety of color, but the seed hardly ever comes 
true. Perhaps the process has not been long enough 
continued. The pansies, which have yielded so much 
beauty and grown to so great a size, develop seed that 
is much more reliable. The fact that seeds revert 
shows the force of heredity and the truth that it per¬ 
sists through many generations. 
At every fat-stock show we find examples of 
thorough breeding. The great variety in any one 
kind of stock is not only marvelous, but very sug¬ 
gestive. The horses are familiar examples. In one 
stall is exhibited the dwarf-like Shetland pony, so 
small that we could almost carry it off on our shoul¬ 
ders ; in another stands the fieet race-horse with well- 
trimmed limbs and slender body; in another is the 
stately coach-horse; in another the strong-limbed, 
broad-footed Clydesdale ; in still another the immense 
J^orman, which crowds the scale far toward the ton 
mark. All these and many others are descended, 
without doubt, from the ancient primitive horse 
which, as we have already seen, was itself a descend¬ 
ant, through a series of evolutions, of the five-toed 
horse of the Miocene period. 
Similar descent could be traced in cattle, sheep, 
hogs, and fowls, but space will permit but one more 
illustration, and that is pigeons. There are the slen¬ 
der, timid mourning-dove; the passenger, with broad 
