Note 53 — Chapter II · —Classes Of Geographic Influences

The relation of pigmentation to climate has long interested geographers as a question of environment; but their speculations on the subject have been barren, because the preliminary investigations of the physiologist, physicist and chemist are still incomplete. The general fact of increasing nigrescence from temperate towards equatorial regions is conspicuous enough, despite some irregularity of the shading.53 This fact points strongly to some direct relation between climate and pigmentation, but gives no hint how the pigmental processes are affected. The physiologist finds that in the case of the negro, the dark skin is associated with a dense cuticle, diminished perspiration, smaller chests and less respiratory power, a lower temperature and more rapid pulse,54 all which variations may enter into the problem of the negroes coloring. The question is therefore by no means simple.