HEREDITY IN HORSES 
Why the Arab Horse Has Shown Such Conspicuous Ability for Endurance in the 
Recent Long Distance Tests! 
H. kK. BusH-BRrown 
Washington, D. C. 
horse in long distance tests calls 
the attention of the public, and 
especially breeders, to the genetic value 
of the thoroughbred blood. 
I use the word here in a general 
meaning and not as applicable solely 
to the group of registered race horses 
known as the ‘English Thoroughbred.” 
In order to be specific let us state the 
anatomical differences of recognized 
types of horses, which perhaps will 
explain why the Arab is such a good 
weight carrier and capable of endurance 
under hardship. 
To begin with, the Arab’s head is 
smaller and broader, his nose finer, his 
eye larger and more prominent and 
alert. His head is articulated onto the 
neck at a more obtuse angle than other 
horses. (See Fig. 16.) 
His chest is broad, giving plenty of 
space for heart and lungs, and his ribs 
are well set out from the spine, giving 
a relatively large space for carrying the 
viscera. 
The bones of his legs are clean and 
very dense as compared with other 
horses and less liable to defects from 
hard usage. He stands with all his 
four feet under him, and with straight 
hind legs. The osselets are small and 
the dewlap usually wanting or vestigial. 
4 BES: recent success of the Arab 
THE ARAB’S SHORT BACK 
These differences are sufficient to 
mark the Arab as a separate family 
among horses, but the five lumbar 
vertebrae instead of the six common to 
all other horses seem to place him in a 
separate species. As this difference is 
now recognized by leading anatomists, 
it may be of importance to those 
interested to see some illustrations 
demonstrating these differences. This 
shortness in the back is usually in the 
lumbar vertebrae five instead of six, 
but it occasionally appears in the dorsal 
instead. 
Figure 17 is a photograph of the five 
lumbar vertebrae of the pure Arab 
Stallion Nim» whose sire and dam were 
only one generation from the desert 
and whose skeleton is in the Museum 
of Natural History in New York. 
Figure 18 shows the six lumbar ver- 
tebrae of the famous thoroughbred 
horse Lexington whose skeleton is in 
the National Museum in Washington. 
There is here a peculiar atavistic 
tendency shown in the angle of the 
spine of the one next to the sacral 
group, it being thrown backward 
instead of forward as though it would 
be one of the sacral vertebrae and thus 
leave only five in lumbar like the Arab 
ancestors. This, however, would have 
made too many sacral. 
I have already published? a long 
series of these to show that all other 
types of horses have twenty-four verte- 
brae in the back except the Arab which 
has twenty-three, but it is no longer 
necessary to convince any one of a fact 
so well established. 
VARIATIONS IN SOME TYPES 
The skeleton of the imported Arab 
stallion Haleb in the National Museum, 
Washington (not yet mounted), has six 
lumbar vertebrae but only seventeen 
dorsal vertebrae, so the shortness of 
his back is maintained although it is 
found in the forward section instead of 
in the lumbar, the usual place for it. 
| The writer is indebted to Mr. A. H. Chubb of the Museum of Natural History of New York 
for many courtesies and cooperation. 
Arabs and Norway ponies. 
Also to Mr. Warren Delano for his research breeding of 
2 Horses and Horse Breeding, by H. K. Bush-Brown, American Breeders Magazine, Vol. II, 
Nos. 2 and 3. 
