ravenously hungry and at the same time splendidly in condition.
Like the wolves, their forebears, their nutritive processes were
rigidly economical and perfect. There was no waste. The last
least particle of what they consumed was transformed into energy.

And Kama and Daylight were like them. Descended themselves from
the generations that had endured, they, too, endured. Theirs was
the simple, elemental economy. A little food equipped them with
prodigious energy. Nothing was lost. A man of soft
civilization, sitting at a desk, would have grown lean and
woe-begone on the fare that kept Kama and Daylight at the
top-notch of physical efficiency. They knew, as the man at the
desk never knows, what it is to be normally hungry all the time,
so that they could eat any time. Their appetites were always
with them and on edge, so that they bit voraciously into whatever
offered and with an entire innocence of indigestion.

By three in the afternoon the long twilight faded into night.
The stars came out, very near and sharp and bright, and by their
light dogs and men still kept the trail. They were
indefatigable. And this was no record run of a single day, but
the first day of sixty such days. Though Daylight had passed a
night without sleep, a night of dancing and carouse, it seemed to
have left no effect. For this there were two explanations first,
his remarkable vitality; and next, the fact that such nights were
rare in his experience. Again enters the man at the desk, whose
physical efficiency would be more hurt by a cup of coffee at
bedtime than could Daylight's by a whole night long of strong
drink and excitement.