Bush-Brown: Heredity in Horses 
i) 
to 
LUMBAR VERTEBRAE OF A FOAL 
A similar tendency to that shown in McKinney in Fig. 7 is illustrated in this skeleton of a foal 
from a pure Arab mare and a Norway sire. Here is shown the 17th dorsal vertebra and one partly 
developed rib. The gristle attachment would no doubt have ossified in a short time, and the other 
floating rib may have been lost in dissecting. 
the tests for long distance under 
service conditions similar to those of 
the Army, for he is especially built for 
that purpose. 
Since the unit character of a short 
back seems to be recessive except in the 
purebred Arab, it quite completely 
explains why the thoroughbred horse 
is so different anatomically although 
he is a product of the Arab by long and 
intelligent breeding, chiefly from male 
Arab ancestry. 
As his name implies he is ‘‘thorough- 
bred’ from the Arab and yet in no 
instance that I know of has he devel- 
oped the twenty-three vertebrae in the 
back. Therefore to maintain the Arab 
type, it must be kept scrupulously 
pure, and this justifies the custom 
among the Arabs in tracing their 
horses’ pedigrees through the dam. 
(Fig. 23.) 
Of course the power of transmission 
of inheritance is not confined to the 
anatomical structure alone. The Thor- 
oughbred is the best horse for a 
short distance for which he has been 
especially developed, and he has cour- 
age and intelligence perhaps equal to 
his Arab ancestry. 
LAWS OF HEREDITY SHOULD BE CLOSELY 
STUDIED 
The facts here assembled seem to 
show that the laws of heredity can be 
pursued with great advantage by a 
more thorough study of variability in 
the anatomy of the horse, especially in 
outbreeding of the pure Arab with the 
kindred types of different anatomy— 
a real field for genetic research. This 
field needs a policy to be pursued by a 
group of men who can follow the 
