to seek. Seth Wright took care not to weaken the Ancon blood by matching
his Ancon ewes with any but males of the same variety, while Gratio
Kelleia's sons were too far removed from the patriarchal times to
intermarry with their sisters; and his grand-children seem not to have been
attracted by their six-fingered cousins. In other words, in the one example
a race was produced, because, for several generations, care was taken to
_select_ both parents of the breeding stock from animals exhibiting a
tendency to vary in the same direction; while, in the other, no race was
evolved, because no such selection was exercised. A race is a propagated
variety; and as, by the laws of reproduction, offspring tend to assume the
parental forms, they will be more likely to propagate a variation exhibited
by both parents than that possessed by only one.

There is no organ of the body of an animal which may not, and does not,
occasionally, vary more or less from the normal type; and there is no
variation which may not be transmitted and which, if selectively
transmitted, may not become the foundation of a race. This great truth,
sometimes forgotten by philosophers, has long been familiar to practical
agriculturists and breeders; and upon it rest all the methods of improving
the breeds of domestic animals, which, for the last century, have been
followed with so much success in England. Colour, form, size, texture of
hair or wool, proportions of various parts, strength or weakness of
constitution, tendency to fatten or to remain lean, to give much or little
milk, speed, strength, temper, intelligence, special instincts; there is
not one of these characters the transmission of which is not an every-day
occurrence within the experience of cattle-breeders, stock-farmers,
horse-dealers, and dog and poultry fanciers. Nay, it is only the other day
that an eminent physiologist, Dr. Brown-Sequard, communicated to the Royal
Society his discovery that epilepsy, artificially produced in guinea-pigs,
by a means which he has discovered, is transmitted to their offspring.