436 On the Tnlieritance of Coat-Colour in Cattle 
largely bred this cross but all the calves have been polled. Mr Hodgson on the 
other hand has found 1 out of 8 to 10 horned. 
{PH) X {RR). This should equal 2 {PR) + 2 {UH) and give half horned and 
half polled. Messrs Hyslop find the majority horned. Mr Richardson finds three- 
quarters horned, and Mr Irving that the horned are in a majority of three to one. 
Mr Irving says that it sometimes happens that the horns do not grow to much size 
but in the majority of cases they are there, and he does not consider that such 
cattle can be described as polled. Mr Tinniswood finds the calves bred this way 
generally horned, perhaps 2 or 3 in twenty would come polled. Mr Hodgson on 
the other hand finds in this case only 1 in 4 to 6 horned and illustrates by three 
blue-grey % s put to a white shorthorn bull last year giving all polled calves. 
{PE) X {PH). This sliould give (PP) + 2 {PH) + {HH), which being inter- 
preted is polled in a majority of three to one. Few breeders make this cross, 
and Messrs Irving, Richardson and Tinniswood have had no experience of it. 
Mr R. Hyslop finds six polled to one horned, and Mr Hodgson says one out of 
6 to 8 horned. These numbers are far from the Mendelian ratio. 
Thus, as in other cases which it has been our misfortune to come across, we 
find approximations to Mendelism, but we do not find Mendelism an accurate 
account of the records provided. The polled {PH) might really be a (PP), it 
cannot be an {HH). and therefore we could account for less than a half being 
horned in the cross {PH) x {HH), but not for more than a half being horned. 
The only explanation could be that polled in a number of cases are latently horned, 
i.e. we cannot distinguish (PP) from {PH). This would account for the horned 
cattle appearing in (PP) x {HH), but not for the usual absence of horns in 
{PH) x {PP), for some reputed {PP)'s would be {PH)'s. Anyhow the further 
pursuit of a somewhat elusive Mendelism in blue-grey cattle did not seem to us 
likely to be profitable. 
(5) Colour History of the Shorthorn. 
The classification of shorthorns into broad categories is extremely simple as 
compared with some other types of domestic cattle. The recognised classes are 
Red {R), this is supposed to contain whole reds; Red ivith a little White {RLW) 
or red with occasional white spots or with white markings ; Red and White {RW), 
i.e. particolour ; Roan {Ro), a mixture of red and white hairs; and White {W). 
The white are not albinos*, having black eyes and occasionally black noses. 
Attempts more or less successful to get rid of the black noses have been ener- 
getically made by breeders. The existence of black pigment in the nose is probably 
not always recorded in the herdbook records. We have seen that breeders of blue- 
grey cattle strive to get shorthorn bulls without black noses, but as there is always 
black pigment in the eye, the question of absence of black pigment in the nose is 
perhaps not of first-class importance in the problem of crossing. It appears 
perfectly certain that eye and nose pigmentation in intercrossing white shorthorns 
* A herd of true albino white cattle (whole white and pink eyes) has been reported to us as 
existing in Sweden, but we have not succeeded in locating it. 
