We have already noted the fact that the sheep is especially adapted to serve man in high latitudes, where he has to provide against the winter's cold. The camel is an even more striking instance in which the value of the creature depends upon climatal peculiarities. It is peculiarly fitted, by its ancestral training and development, for the use of men who dwell in arid countries. In the olden days of the later Tertiary epoch, creatures akin to the camels appear to have been widely distributed, and were probably adapted to considerable variations of environment. Within the time of which we know something by history, these forms have been limited to the arid districts of southwestern Asia and northern Africa. It is not certain that we know the originally wild form of either of the two species, the double-humped or single-humped camels. Wild members of each exist, but they may be the descendants of the domesticated forms. It seems probable that long before the building of the Pyramids the people of the deserts had learned how to profit from the very peculiar qualities of this strangely provided beast, which in several distinct ways is singularly fitted to serve the needs of man in arid lands. The large and well-padded foot of this creature is well adapted for treading a surface unsoftened by vegetation. Its peculiar stomach enables it to store water in such a manner that it can go for days without drink. In the humps upon its back, as in natural pack-saddles, it may harvest a share of the nutriment which it obtains from occasional good pasturages, the store being laid away in the form of fat which may return to the blood when the creature would otherwise starve. So important have these peculiarities been found by men who have domesticated the camel, that on them have rested many of the most interesting features of race development in the history of our kind. In the territories along the eastern and southern shores of the Mediterranean, and in a large part of southern and central Asia, the camel has done service to man which elsewhere has been performed by sheep, cattle, and horses. In those parts of the world the share which these domesticated animals have had in the development of man has been relatively small. The camel has given the strength for burdens, hair for clothing, and often flesh to the needy men of the desert. [Illustration: The Halt in the Desert at Night--The Story Teller]