hey should be worth
fifteen thousand," said Horace. "But I'm much afraid they won't live
unless we can get the mother to travel with them. But now that we have
the cubs it should be rather easy to catch her, and maybe the father,
too."

They set the cage back into the hollow made by the ruined burrow, and
laid spruce branches over it so that it was well hidden. Then they
wrapped the jaws of the trap with strips of cloth so that they would
not cut the fox's skin, and set it directly in front of the cage.
Finally they scattered dead leaves over the trap. The cubs themselves
would act as bait.

"A fox never deserts her young," Horace said. "She's sure to come back
to-night, probably along with her mate, to carry off the cubs, and
we've a good chance to catch one or both of them."

It seemed dangerous to go away and leave that precious cageful of
little foxes at the mercy, perhaps, of the beaver trappers; perhaps
prowling lynxes or wolves. However, the boys had to take the risk. As
to the trappers, they had seen nothing of them for so long that they
had little fear of them.

They went back to camp and tried to pass the time; but they could talk
of nothing except black foxes. Fred conceived the idea of using their
stock to start a breeding establishment of their own, and Macgregor was
elaborating the plan, when suddenly he stopped with a frown.

"Is it so certain that the parents of those cubs are black?" he asked.
"I've heard that black foxes are an accident, a sport, and that the
mother or father is very often red."

"That's something that naturalists have never settled," replied Horace.
"Some think that the black fox is a distinct strain, others that it's
merely a 'sport,' as you say. However, when all the cubs in the litter
are pure black, I think it's safe to assume that the parents are black
also."

It was scarcely daylight the next morning before the boys were hurrying
along the blazed trail again. Shaking with suppressed excitement, they
approached the ravine of the foxes. When they came in sight of the den
and the cage their anticipation was succeeded by bitter disappointment.
The trap was undisturbed. Nothing had been caught. The cubs were
still in the cage, as frightened as ever.

But they found that one at least of the old foxes had visited the
place, for the dry leaves were disturbed; there were marks of sharp
teeth on the willows of the cage, and inside the cage were the tails of
a coupl