•184 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1921. 



2. In males loss begins at times even before the adult stage is 

 reached ; and after 55 there are very few men in whom some degree of 

 loss at least has not taken place. 



3. Wide individual differences exist also in this respect. 



COMPARISONS. 



1. Suitable data for comparison are scarce. From what is avail- 

 able it appears that the pigmentation of both hair and eyes in the 

 Old Americans is much like that of the present population of Great 

 Britain, though the latter appears to show some excess of both dark 

 eyes and dark hair. 



2. As to changes with time, it seems probable that in both Great 

 Britain and the United States there is taking place a slow progress 

 towards a darker pigmentation of both eyes and hair, though the 

 fact needs definite confirmation. 



