156 EGBERT BENNETT BEAN 



3. The eruption of the teeth in relation to race 



The American white is taken as the standard. Order of erup- 

 tion: (1) Filipino, (2) French, (3) American Indian, (4) American 

 white, (5) German. The time at which 50 per cent of the teeth 

 have erupted: French 6 months to 1 year earher than American 

 white. German 6 months to 2 years later than American white. 

 American Indian is from 1 to 6 months earUer than the Ameri- 

 can white. Fihpino 1 to 4 years earher than American white. 



4. The eruption of the teeth in relation to sex 



American girls are from 0,2 years for the incisors, to 1.4 years 

 for the canines, earlier than the American boys. German girls 

 are from 0.3 years for the incisors to 1.1 years for the canines, 

 earlier than the German boys. Filipino girls and boys are more 

 nearly alike in the time of eruption. 



5. The eruption of the teeth in relation to school grade 



The modal grade is the grade which has the greatest number of 

 individuals at each age. For instance at 7 years of age the 

 second grade is the modal grade. At ages 7 to 14 inclusive, 

 children above the modal grade have 0.8 more teeth, and children 

 below the modal grade have 0.9 fewer teeth, than children at the 

 modal grade. The difference is greatest at 10 and 11 years, i.e., 

 during the most rapid eruption of the second part of the period of 

 second dentition, when children above the modal grade have 1.8 

 more teeth, and children below the modal grade have 1.5 fewer 

 teeth, than children at the modal grade. 



6. The eruption and decay of the teeth in relation to 7norphologic 



form 



Two types, extremes: (1) Hypo- equals infantile, round head, 

 broad face and nose, large parietal and small occipital region of 

 head. (2) Hyper- equals long head, face, nose, small parietal, 

 large occipital region of the head (table 3) : 



