[Sidenote: Effects of climate.]

Both the direct and indirect physical effects of environment thus far
instanced are obvious in themselves and easily explained. Far different
is it with the majority of physical effects, especially those of
climate, whose mode of operation is much more obscure than was once
supposed. The modern geographer does not indulge in the naive hypothesis
of the last century, which assumed a prompt and direct effect of
environment upon the form and features of man. Carl Ritter regarded the
small, slit eyes and swollen lids of the Turkoman as "an obvious effect
of the desert upon the organism." Stanhope Smith ascribed the high
shoulders and short neck of the Tartars of Mongolia to their habit of
raising their shoulders to protect the neck against the cold; their
small, squinting eyes, overhanging brows, broad faces and high cheek
bones, to the effect of the bitter, driving winds and the glare of the
snow, till, he says, "every feature by the action of the cold is harsh
and distorted."[48] These profound influences of a severe climate upon
physiognomy he finds also among the Lapps, northern Mongolians,
Samoyedes and Eskimo.

[Sidenote: Acclimatization]

Most of these problems are only secondarily grist for the geographer's
mill. For instance, when the Aryans descended to the enervating lowlands
of tropical India, and in that debilitating climate lost the qualities
which first gave them supremacy, the change which they underwent was
primarily a physiological one. It can be scientifically described and
explained therefore only by physiologists and physico-chemists; and upon
their investigations the geographer must wait before he approaches the
problem from the standpoint of geographical distribution. Into this