THE QUEST FOR ; THE WILD HORSE 97 
angle with the throat instead of a curve, are as 
characteristic of a young colt as of the Equus 
PrejvcilsJcii. But, apart from all external differences 
between the ass and the horse, lies the inexplicable 
fact that the latter adapts itself to changed conditions 
in almost all climates, while the former does not. 
Under human care and selection, the horse varies so 
rapidly, that we meet with all extremes, from the 
dray-horse to the Shetland, and all colours from 
black to white. But the ass in the last five thousand 
years has varied little. It will not thrive except in 
hot climates, and centuries of careful breeding have 
not caused it to change colour further than from grey 
to white , 1 and have done little to make it a pleasant 
animal to ride, or big enough for heavy draught. 
These facts give a starting-point from which we may 
judge whether or not the Equus PrejvalsJcii is of the 
true stock. Let those recently brought to Russia be 
made the nucleus of a herd, and the variations of 
successive generations be noted. Then if they are 
true horses, they will vary first in colour, then in 
shape, and human selection ought to be able to 
guide the varieties towards different types. If, on 
the other hand, they be asses, they will refuse to 
vary, and remain true to the type of the steppes of 
Dsungaria. 
Even in our own New Forest, this difference 
between the horse and the ass is curiously persistent. 
1 There are black donkeys, but most appear to be instances 
of “ melanism ” rather than of colour gradation. 
H 
