THE STUDY OF NATURAL SELECTION 143 



associated with hair color and eye color in such a way that the darker 

 classes have the greater recuperative power. 46 



Pearson 47 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 48 from his study of pig- 

 mentation 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 sur- 

 veys or school medical officer's reports are necessary for their detection. 49 



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 pigmenta- 

 tion to selection from an entirely different, and most important, side. 60 

 He seeks to determine the relationship between skin color and survival 

 in tropical sunlight. He concludes that the lack of pigmentation is 



48 These conclusions rest solely on the hospital observations. I omit those 

 which involve questions concerning the liability to infection, since they require 

 a knowledge of the distribution of pigmentation in the general population. 

 Such comparisons involve the use of some such basis as the British Association 

 standards or the general anthropometric surveys, which may not be valid for the 

 particular district or social class from which the hospital or asylum inmates are 

 drawn. This was true, for instance, in Strumball's pioneer study, which is 

 highly suggestive rather than conclusive. Again, in attempting to settle the 

 question of differential incidence by an analysis of hospital populations there is 

 the danger of a large personal equation in the appraisal of non-measurable char- 

 acters. Neither of these difficulties are met when studies of recuperative power 

 are made by a single observer. See also K. Pearson, Biometrika, 8: 39, 1912. 



47 Unpublished results quoted by Saunders, Biometrika, 8 : 355, 1912. 



48 A. M. C. Saunders, ' ' Pigmentation in Relation to Selection and to Anthro- 

 pometric Characters," Biometrika, 8: 354-369, 1912. 



49 Miss Elderton, ' ' On the Relation of Stature and Weight to Pigmenta- 

 tion," Biometrika, 8: 340-353, 1912, concludes from her study of the relation- 

 ship between hair and eye color and weight and stature : " So far as the material 

 goes we find that types of hair and eye color are not associated to any substan- 

 tially significant extent with divergencies in height and weight in children 

 between the ages of seven and fourteen, inclusive." It must be noted that Miss 

 Elderton 's problem was in large part undertaken to determine the influence of 

 racial heterogeneity on stature, in its relation to environmental influence. 



"Chas. E. Woodruff, "The Effect of Tropical Light on White Men," 1905. 

 Also, Science, N. S., 31 : 620, 1910. 



