Page:Popular Science Monthly Volume 84.djvu/147

Rh associated with hair color and eye color in such a way that the darker classes have the greater recuperative power.

Pearson has also demonstrated correlation of $$r =.19$$ between health and hair color and $$r =.07$$ between health and eye color for data relating to 2,317 boys. Similar results were obtained for girls.

But, on the other hand, there are contradictory evidences. For instance, the conclusion reached by Saunders from his study of pigmentation and susceptibility to diseases in Birmingham school children is that pigmentation is not a factor in selection.

He also finds that relationships between pigmentation and stature and weight, if they exist, are of so delicate a nature that much more refined data than those furnished by the ordinary anthropometric surveys or school medical officer's reports are necessary for their detection.

The discrepancy between his results and those of MacDonald is possibly due to differences in the nature of the populations dealt with. Perhaps, too, data derived from the official examination of school children are less reliable than the hospital returns.

Woodruff has attacked the problem of the relationship of pigmentation to selection from an entirely different, and most important, side. He seeks to determine the relationship between skin color and survival in tropical sunlight. He concludes that the lack of pigmentation is