18 BULLETIN 1350, IT. S. DEPARTMENT OF AGRICULTURE 
The brush should be reasonably long, in order to balance properly 
with the length of the body. The general principles determining 
the quality of fur on other parts of the body are equally applicable 
to the brush. 
CONFORMATION 
Conformation involves the individual structure of each part as a 
unit. A defect in any part offsets to some extent an otherwise per- 
fect structure. Some parts, as the chest, back, loin, or leg, are rela- 
tively of greater importance than the others; a deficiency in such 
parts would have more effect on the serviceability of the„ whole than 
a similar inferiority elsewhere. 
Constitutional vigor is evidenced by a well-developed heart girth, 
chest, front flank, and loin, and both vixen and dog should be deep, 
wide, and well coupled in these regions. There should be no indica- 
tion of a pinched appearance behind the shoulders or in the loin. 
If breeding foxes are strong in these regions it is safe to assume that, 
other things being equal, they have strong lungs and heart, and con- 
sequently are stronger, healthier, and more able to resist disease. 
BREEDING 
It is to be constantly borne in mind that blue foxes are not domes- 
ticated animals in any sense of the term. The purpose of breeding 
blue foxes is to produce good fur and to improve the stock. The 
business of blue-fox ranching is comparatively new, and he who would 
succeed in it must give it careful thought, study the moods of the 
animals, and prepare himself to meet intelligently emergencies as 
they arise. Many companies formed for the sole purpose of raising 
foxes have failed because of the great difficulty in hiring a keeper 
having the necessary personal interest in the welfare of the animals. 
The more thoroughly a man studies breeding practices and his foxes, 
the more closely he may approach a uniform degree of success in his 
breeding operations. 
The only method of breed improvement that the blue-fox rancher 
can use, unless he is raising the animals in pens, is grading and close 
culling of inferior stock. On islands where steel traps are used 
instead of trap-feed houses, all animals trapped are killed. In this 
way the best may be killed and the poorest left for breeding stock. By 
use of trap-feed houses, however, the poorest animals can be killed 
and the best liberated for breeders. On islands formerly producing 
pelts having a high percentage of white hairs, this condition has now 
largely been eliminated by following this s}'stem, and the stock is 
darker and clearer colored. 
Grading is the mating of a common or relatively unimproved 
animal with one that is more highly improved. In the case of do- 
mestic animals the male is selected as the improved one of the pair 
for reasons of economy. In the blue-fox business, however, it is well 
for the improvement to be made both ways. Improvement by grad- 
ing is, of course, limited to the foxes on a particular island. This 
method distributes breed excellence rapidly and with certainty; 
that is, the unimproved blood soon becomes insignificant and finally 
disappears. Only those individuals meeting standard requirements 
should be retained for breeding. 
