ONTOGENETIC DEVELOPMENT OF SKIN COLOR OF NEGRO. 7 



not including) 5 years; 5 to 9; 10 to 19; 20 to 39; 40 to 59. Finally, 

 for reasons that will be discussed more fully later, the measurements 

 taken at Bermuda and at Jamaica are averaged separately (table i). 



TABLE I. Average grade of N in skin color of various negro-white crosses, by age classes. 



In table i the second Bermuda entry has been smoothed by the 

 exclusion of five dark sisters who, belonging to an exceptionally dark 

 strain, have rendered the average unduly high. The number of meas- 

 urements from which the averages were obtained varies for the different 



10 20 30 40 50 60 

 Age. years 



FIG. i. Polygon showing graphically the 

 varying percentages of N in skin color 

 for each age of life (Bermuda). 



in 



k 



8 15 



U 



10 20 30 40 

 Age, years 



FIG. 2. Polygon showing graph- 

 ically the varying percentages 

 of N in skin color for each age 

 of life (Jamaica). 



classes from over 100 down to u. It appears that the proportion of 

 black in the skin increases to about the age of 10 or 12 years and then 

 slowly diminishes, a fact to which Simonot (1862, p. 147) called atten- 

 tion. On careful consideration of these facts it seemed desirable to 

 exclude from further consideration (except as indicated) all measure- 

 ments made on individuals under the age of 2 years, on the ground 



