in their second plumage the feathers all become spangled or tipped with
a dark round spot. (34. These facts are given on the high authority of
a great breeder, Mr. Teebay; see Tegetmeier s Poultry Book, 1868, p.
158. On the characters of chickens of different breeds, and on the
breeds of the pigeon, alluded to in the following paragraph, see
Variation of Animals, etc., vol. i. pp. 160, 249; vol. ii. p. 77.)
Hence in this breed variations have occurred at, and been transmitted
to, three distinct periods of life. The Pigeon offers a more remarkable
case, because the aboriginal parent species does not undergo any change
of plumage with advancing age, excepting that at maturity the breast
becomes more iridescent; yet there are breeds which do not acquire
their characteristic colours until they have moulted two, three, or
four times; and these modifications of plumage are regularly
transmitted.
INHERITANCE AT CORRESPONDING SEASONS OF THE YEAR.
With animals in a state of nature, innumerable instances occur of
characters appearing periodically at different seasons. We see this in
the horns of the stag, and in the fur of Arctic animals which becomes
thick and white during the winter. Many birds acquire bright colours
and other decorations during the breeding-season alone. Pallas states
(35. Novae species Quadrupedum e Glirium ordine, 1778, p. 7. On the
transmission of colour by the horse, see Variation of Animals and
Plants under Domestication, vol. i. p. 51. Also vol. ii. p. 71, for a
general discussion on Inheritance as limited by Sex. ), that in
Siberia domestic cattle and horses become lighter-coloured during the
winter; and I have myself observed, and heard of similar strongly
marked changes of colour, that is, from brownish cream-colour or
reddish-brown to a perfect white, in several ponies in England.
Although I do not know that this tendency to change the colour of the
coat during different seasons is transmitted, yet it probably is so, as
all shades of colour are strongly inherited by the horse. Nor is this
form of inheritance, as limited by the seasons, more remarkable than
its limitation by age or sex.
INHERITANCE AS LIMITED BY SEX. The equal transmission of characters
to both sexes is the commonest form of inheritance, at least with those
animals which do not present strongly-marked sexual differences, and
indeed with many of these. But characters are somewhat commonly
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