442 On the Inheritance of Coat-Colour in Cattle 
some few were overlooked. So that the cross is one of extreme rarity. In these 
91 cases the calves were in 86 cases white, in four cases roan*, and in one case red -I*. 
The American Herdhook examined for other matters produced incidentally a case 
of W -xW = RW. Thus Coates Herdhook indicates that in 5| per cent, of cases 
white does not breed true to white. We are therefore driven to the conclusion 
that, if the records are to be trusted, there are latent determinants in white short- 
horns or in some white shorthoi'ns which under certain circumstances can be 
called into play. This view is confirmed by another consideration. Some wild 
white cattle, like the late Chartley Herd with its representatives at the Zoological 
Gardens, have black muzzles and black ear-linings. They are reputed to drop 
occasionally black or red calves. Other herds of wild white cattle have black 
noses and red inside the ears, and have bred absolutely true to this type for at 
least a century. As we have seen, the white shorthorns breed generally true 
to their type. The cross wild white cow x shorthorn white bull gives a hybrid 
pure white cow, but such pure white cows, if crossed with a shorthorn white bull, 
may produce a considerable percentage of both roan and red as well as white 
calves. In other words, while wild white cattle of the type considered breed 
absolutely and the white shorthorns sensibly true to type, and while the hybrid 
is pure white, the hybrids' offspring by white shorthorns segregate into colours 
occurring in the near ancestry of the shorthorn, and possibly but not probably in 
the distant ancestry of the wild white. These facts, coupled with the experience 
that white shorthorns if crossed will, although rarely, give roans and reds seem to 
show the existence of latent colour determinants in the whites depending upon 
their ancestral history. The phenomena described are similar to those noted in 
albino white mice, which carry in latent form traces of their colour ancestry, traces 
which can become patent under various crossings. 
The simplest Mendelian formula would be based on considering the white as 
recessive and the red as dominant, and the roan as hybrid, i.e. 
{RR)x{WW) = {Ro), 
and this is roughly an expression of some of the facts of the case. Thus ( WW)y.{ WW) 
gives (ITTT''^) in all but 5-i per cent, of cases. In 196 crosses of {RR) x {RR) we find 
156 give (RR), or in about 79"5 per cent, of cases. But, besides about 3 per cent, 
of roans, we have 12 per cent, of calves with white markings and 5 5 per cent, of 
particoloured. We are thus compelled to consider all red, as Ave have just con- 
sidered all white, as either consisting of several subclasses onl}' to be discovered 
by breeding, some all reds being really heterozygous, or else as containing latent 
white marking and particolour determinants. But the difficulty does not stop 
here, there appear to be authentic cases of (RR) x (RR) giving (TP IT). Thus we 
find Favourite Duke (R) got out of Clara 3rd (R) not only a normal red bull calf, 
but a red and white cow calf and the white cow calf Clara 5th]: and the (R) Heydon 
* Bull calves : Unnamed, Vol. xxxvi. p. 277 ; Shaftesbury, Vol. xxxvii. p. 292. Cow calves : Crystal 
Valley, Vol. xliv. p. 273; Seam, Vol. xlviii. p. 809. Other cases in American Herdhook. 
t Cow calf, Bright Anna 2nd, Vol. xliii. p. 318. % Coates' Herdhook, Vol. xli. p. 623. 
