48 



SUCCESSFUL FARMING 



FIG. 9. The cups in the central 

 incisors above hava practically dis- 

 appeared at nine years. 



FIG. 10. The cups in the inter- 

 mediate incisors above have dis- 

 appeared at ten years. 



FIG. 11. At eleven years the 

 tables on the upper jaw are nearly 

 smooth. 



FIG. 12. Note the smooth tables 

 and the length of the teeth showing 

 considerable wear at fifteen years. 



FIG. 5. Complete set of lower 

 permanent incisors showing deep cups 

 ao five years. 



FIG. 6. The cups in the lower 

 central incisors have nearly disappeared 

 and the tables are smooth at six years. 



FIG. 7. The cups in the lower in- 

 termediate pair of incisors have dis- 

 appeared at seven years. 



FIG. 8. The cups in the lower 

 corner pair of incisors have disappeared 

 and the tables are all worn smooth at 

 eight years. 



FIG. 13. Showing a comparison 

 of the angles of the jaw at five and 

 twenty-one years. Note the acute 

 angle of the teeth at twenty-one. 



FIG. 14. Showing order of appearance 

 of the permanent incisors. The central pair 

 at 2 to 3 years. The intermediate pair at 

 3 to 4 years. The corner or outside pair at 

 4 to 5 years. 



NOTE. Photographs showing teeth at various ages, by courtesy of Prof. S. T. 

 Simpson, Agricultural Extension Service, Missouri Experiment Station. 



