18 LIST OF ILLUSTRATIONS. 



Page 



Section of Grinder, 63 



Two-Year-Old Mouth, 64 



Toree-Year-Old Mouth, 64 



Four-Year-Old Mouth, 66 



Five- Year-Old Mouth, 67 



Six-Year-Old Mouth, 68 



Seven-Year-Old Mouth ^ 



Aged Mouth. 69 



