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435 
of such reversion. As he puts it, " it is desirable that the white shorthorn should 
be of white parentage," and " the Galloway a pure Galloway." 
(b) More segregation takes place when the hybrid generation is crossed with 
either original stock. Red hair appears, the white shorthorn is replaced by white 
with black nose and ears, and this or pure white appears from the cross 
(BW) X (BE). Our hope therefore that a simple Mendelian formula might be 
tested on this case — the only one in which we knew of two whole colour cattle 
of different races being habitually crossed — has failed. Our enquiries were, we 
believe, justified, however, by the apparent simplicity of black x white = blue- 
grey*. We did not think actual colour statistics in this case worth collecting, for 
if we must deal with more complex colour categories, it is at once best to turn to 
breeds like the shorthorn and Guernsey, for which ample colour statistics are 
already on record. So far as it is pos.sible to make a comparison between rough 
experience of the present kind on blue-grey cattle and more definite quantitative 
experience on mice, the colour residts of crossing are in many points strikingly 
like the Oxford experience with Japanese waltzing and albino white mice. It 
will need a complex allelomorph to describe these colour changes, if indeed the 
phenomena can be thus described at all. 
(4) Blue-Greij Cattle. Horn I nlieritance. 
It seemed worth considering whetiier a second character, the horns, would 
admit of a simple Mendelian analysis. The black Galloways are polled cattlef, 
and the white shorthorns, horned. We can represent these respectively by {PP) and 
(HH), Siud we have to enquire as to the following results: {PP) x {HH) = {PH), 
(PH) X (PP), (PH) X (HH) and (PH) x (PH). 
First, (PP) X (HH) gives theoretically the blue-grey (PH). Actually Messrs 
Harrison say (PH) are " chiefly " polled, and Mr de Vere Irving finds that about 
one in twenty of (PH) is horned. Thus "polled" is dominant, but it is not 
absolutely dominant. Mr Irving has not found that exceptions are to be associated 
with want of pedigree in the Galloway, and he has found no difference with regard 
to horns between J" (PP) x $ (HH) and the more usual cross $ (PP) x J" (HH). 
Mr Robert Tinniswood agrees on this point, and finds the result polled if both sire 
and dam are pure bred. Mr Hodgson finds not more than about 1 in 30 to 40 
horned ; he considers that this is usually due to impurity in the Galloway 
pedigree, but horns may occur with exceptionally well bred sire and dam. 
(PH) X (PP). This cross should give (PP). Mr Irving finds the offspring 
are polled. Mr Richardson says that they are all polled. Mr Tinniswood has not 
* As a matter of fact this blue-grey is, to judge by hair samples, simply a blend of white and black 
hairs, varying in proportion from almost pure black to a large majority of white. 
t Our English informants state that the Galloway is in their experience polled. If the breed now 
contained (PH)'s, (////)'s would appear. Boyd Dawkins, Quart. Journal Geol. Soc. 1867, p. 177, says 
that in the 18th century Galloways were not polled, but his evidence for universality of horns seems 
far from conclusive. Further details as to the crossing of polled and horned breeds will be given in the 
next number of this Journal. 
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