VE T ERIN A R T DENTAL S UllGER T. 



143 



Second At what age do they cease to grow, or 

 do they grow throughout life? 



Third If they cease to grow, how is their free 

 surface maintained? 



Drs. Hughes, Grange and Liautard responded, 

 and their communications are here inserted : 



Joseph Hughes, M. R. C. V. S., Professor of 

 Anatomy at the Chicago Veterinary College, says: 

 " I would say that at one time I was particularly 



FIG. 32. 



Upper jaw, showing the roots of the molar teeth ; i", 

 canine; i', 2', 3', incisors; i, 2, 3, 4, 5, 6, molars; g, fangs of 

 fourth molar. 



interested in that question, and sought every oppor- 

 tunity to determine as to when molar teeth stop 

 growing. I proved this much to my satisfaction. 

 As soon as a molar tooth is fully erupted and comes 

 into wear, the pulp in the cavity commences to shrink, 

 and in doing so produces layer after layer of yellow 

 osteo-dentine. The shrinkage still continuing, the 

 pulp cavity soon becomes filled and at the same time 

 the fangs commence forming, being produced by the 

 pulp which is almost completely atrophied by this 



