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
whose transmission 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.

But a race, once produced, is no more a fixed and immutable entity than
the stock whence it sprang; variations arise among its members, and as
these variations are transmitted like any others, new races may be
developed out of the pre-existing one 'ad infinitum', or, at least,
within any limit at present determined. Given sufficient time and
sufficiently careful selection, and the multitude of races which may
arise from a common stock is as astonishing as are the extreme
structural differences which they may present. A remarkable example of
this is to be found in the rock-pigeon, which Dr. Darwin has, in our
opinion, satisfactorily demonstrated to be the progenitor of all our
domestic pigeons, of which there are certainly more than a hundred
well-marked races. The most noteworthy of these races are, the four
great stocks known to the "fancy" as tumblers, pouters, carriers, and
fantails; birds which not only differ most singularly in size, colour,