ONTOGENETIC DEVELOPMENT OF SKIN COLOR OF NEGRO. 7 



not including) $ years; $ to 9; 10 to 19; ao to 39; 40 to S9- 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-while 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 &0 60 

 Ag«, yoan 



Pio, t. — Polygon showing graphically the 

 vorylnB pcrccntaceB o{ N in skin color 

 (or each age ol life (Bermuda), 



to 20 .10 40 

 Ago, yoofi 



Pio, ».— Polygon ihowlng graph* 

 ically the varying pcrcentagci 

 of N in ilcin color (or each age 

 of life (Janiaicaj. 



classes from over loo down to ir. It appears that the proportion of 

 black in the skin increases to about the age of lo 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 



