r
ten other species of Fringillidae, and some of the hybrids are almost
completely fertile; but we have no evidence that any distinct breed has
originated from such crosses. Notwithstanding the modern domestication of
the canary, many varieties have been produced; even before the year 1718 a
list of twenty-seven varieties was published in France,[480] and in 1779 a
long schedule of the desired qualities was printed by the London Canary
Society, so that methodical selection has been practised during a
considerable period. The greater number of the varieties differ only in
colour and in the markings of their plumage. Some breeds, however, differ
in shape, such as the hooped or bowed canaries, and the Belgian canaries
with their much elongated bodies. Mr. Brent[481] measured one of the latter
and found it eight inches in length, whilst the wild canary is only five
and a quarter inches long. There are topknotted canaries, and it is a
singular fact, that, if two topknotted birds are matched, the young,
instead of having very fine topknots, are generally bald, or even have a
wound on their heads.[482] It would appear as if the topknot were due to
some morbid condition which is increased to an injurious degree when two
birds in this state are paired. There is a feather-footed breed, and
another with a kind of frill running down the breast. One other character
deserves notice from being confined to one period of life and from being
strictly inherited at the same period: namely, the wing and tail feathers
in prize canaries being black, "but this colour is retained only until the
first moult; once moulted, the peculiarity ceases."[483] Canaries differ
much in disposition and character, and in some small degree in song. They
produce eggs three or four times during the year.

{296}

GOLD-FISH.

Besides mammals and birds, few animals belonging to the other great classes
have been domesticated; but to show that it is an almost universal law that
animals, when removed from their natural conditions of life, vary, and that
races can be formed when selection is applied, it is necessary to say a few
words on gold-fish, bees, and silk-moths.

Gold-fish (_Cyprinus auratus_) were introduced into Europe only two or
three centuries ago; but it is believed that they have been kept in
confinement from an ancient period in China. Mr. Blyth[484] suspects from
the analogous variation of other fishes that golden-coloured fish do not
occur in a s