The Variation of Animals and Plants under Domestication, vol 2 | Page 6

period been crossed, and a character derived from this
cross, after having disappeared during one or several generations,
suddenly reappears. A third class, differing only in the manner of
reproduction, might be formed to include all cases of reversion effected
by means of buds, and therefore independent of true or seminal
generation. Perhaps even a fourth class might be instituted, to include

reversions by segments in the same individual flower or fruit, and in
different parts of the body in the same individual animal as it grows old.
But the two first main classes will be sufficient for our purpose.
REVERSION TO LOST CHARACTERS BY PURE OR
UNCROSSED FORMS.
Striking instances of this first class of cases were given in the sixth
chapter, namely, of the occasional reappearance, in variously-coloured
breeds of the pigeon, of blue birds with all the marks characteristic of
the wild Columba livia. Similar cases were given in the case of the fowl.
With the common ass, as the legs of the wild progenitor are almost
always striped, we may feel assured that the occasional appearance of
such stripes in the domestic animal is a case of simple reversion. But I
shall be compelled to refer again to these cases, and therefore here pass
them over.
The aboriginal species from which our domesticated cattle and sheep
are descended, no doubt possessed horns; but several hornless breeds
are now well established. Yet in these--for instance, in Southdown
sheep--"it is not unusual to find among the male lambs some with small
horns." The horns, which thus occasionally reappear in other polled
breeds, either "grow to the full size," or are curiously attached to the
skin alone and hang "loosely down, or drop off." (13/1. 'Youatt on
Sheep' pages 20, 234. The same fact of loose horns occasionally
appearing in hornless breeds has been observed in Germany; Bechstein
'Naturgesch. Deutschlands.' b. 1 s. 362.) The Galloways and Suffolk
cattle have been hornless for the last 100 or 150 years, but a horned calf,
with the horn often loosely attached, is occasionally produced. (13/2.
'Youatt on Cattle' pages 155, 174.)
There is reason to believe that sheep in their early domesticated
condition were "brown or dingy black;" but even in the time of David
certain flocks were spoken of as white as snow. During the classical
period the sheep of Spain are described by several ancient authors as
being black, red, or tawny. (13/3. 'Youatt on Sheep' 1838 pages 17,
145.) At the present day, notwithstanding the great care which is taken
to prevent it, particoloured lambs and some entirely black are

occasionally, or even frequently, dropped by our most highly improved
and valued breeds, such as the Southdowns. Since the time of the
famous Bakewell, during the last century, the Leicester sheep have
been bred with the most scrupulous care; yet occasionally grey-faced,
or black-spotted, or wholly black lambs appear. (13/4. I have been
informed of this fact through the Rev. W.D. Fox on the excellent
authority of Mr. Wilmot: see also remarks on this subject in an article
in the 'Quarterly Review' 1849 page 395.) This occurs still more
frequently with the less improved breeds, such as the Norfolks. (13/5.
Youatt pages 19, 234.) As bearing on this tendency in sheep to revert to
dark colours, I may state (though in doing so I trench on the reversion
of crossed breeds, and likewise on the subject of prepotency) that the
Rev. W.D. Fox was informed that seven white Southdown ewes were
put to a so-called Spanish ram, which had two small black spots on his
sides, and they produced thirteen lambs, all perfectly black. Mr. Fox
believes that this ram belonged to a breed which he has himself kept,
and which is always spotted with black and white; and he finds that
Leicester sheep crossed by rams of this breed always produce black
lambs: he has gone on recrossing these crossed sheep with pure white
Leicesters during three successive generations, but always with the
same result. Mr. Fox was also told by the friend from whom the spotted
breed was procured, that he likewise had gone on for six or seven
generations crossing with white sheep, but still black lambs were
invariably produced.
Similar facts could be given with respect to tailless breeds of various
animals. For instance, Mr. Hewitt (13/6. 'The Poultry Book' by Mr.
Tegetmeier 1866 page 231.) states that chickens bred from some
rumpless fowls, which were reckoned so good that they won a prize at
an exhibition, "in a considerable number of instances were furnished
with fully developed tail-feathers." On inquiry, the original breeder of
these fowls stated that, from the time when he had first kept them, they
had often produced fowls furnished with tails; but that these latter
would again reproduce rumpless chickens.
Analogous