88 
PROFESSOR K. PEARSON AND DR. A. LEE ON 
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Here again it seems to me that the most we can safely do is to consider that on a 
suitable scale the relative lengths occupied by the classes of coat-colours recognised 
by thoroughbred horse breeders would be somewhat as follows :—- 
bl. 
bl./br. 
br./bl. 
br. br./b. ' b./br. 
b. 
b./cb. ! ch./b. oh. 
ch./ro. ro./eh. 
ro. 
r0 /g r - 
gr /ro. j gr. 
X 
T2 
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1-31 
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o 
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8 
The reader must carefully bear in mind that these represent scale-lengths occupied 
by the coat-colour and not the frequency of horses of these individual coat-colours. 
What we are to understand is this : that if eye-colour in man and coat-colour in 
horses were measured on such quantitative scales as we have given in skeleton, then 
the distribution of the frequency of the several colours would be very approximately 
normal. The actual skeleton scales are represented in the accompanying diagram, 
which puts them at once before the eye. 
Normal Scale of Colour Ranges in Thoroughbred Horses, 
br/bl. b/br. ch/b. 
Black 
Bro 
wn 
Bag 
Chestnut 
Elfbc 
br/b. bjcFi. 
Normal Scale of Eye Colour Ranges in Nan. 
Very Dark 
Brown, Black 
Dark Blue, 
Blue 
Dark Brown 
Brown 
Hazel 
DarkGrey 
Grey 
Blue-Green 
Light 
Blue 
LightBrov, 
in 
(5.) It is necessary here to draw attention to a distinction of some importance in 
heredity, namely, that between blended and exclusive inheritance. In my treatment 
of the law of ancestral heredity,* it is assumed that we have to deal with a quanti¬ 
tatively measurable character, and that the ancestry contribute to the quantity of 
this character in certain proportions which on the average are fixed and follow certain 
definite numerical laws. Such an inheritance is blended inheritance. But another 
* ‘ Roy. Soc. Proc.,’ vol. 62, p. 386, 
