"GUMMING IT." 143 



out more rapidly than the upper, the cause of which 

 is perhaps owing to the superiority of the latter in size 

 and strength. The crown surface of the lower rows 

 is slightly concave, the upper rows slightly convex. 

 The result is that the lower center teeth are sometimes 

 worn to their sockets, which renders the mastication 

 of hard food impossible. At first, however, there is 

 no interference with mastication, and it is usually only 

 in old age that the deformity reaches its worst stage. 

 There is no remedy for the defect, but its progress 

 may be retarded by the use of soft food. * 



" (C.) Lack of regularity in the length of the rows 

 becomes the cause, in horses a little advanced in age, 

 of a peculiar deformity in the first upper and the last 

 lower grinders. Generally the upper range passes that 

 of the lower by some lines, the first upper grinder lap- 

 ping over; but sometimes the case is the reverse, the 

 last lower grinder projecting beyond the last upper. 

 The projecting part of the tooth grows till it reaches 

 the opposite jaw, when, unless it is filed or chiseled off, 

 the most serious consequences will follow. 



" (D.) When a tooth is entirely deficient, the oppo- 

 site tooth grows till it fills the void ; then, no remedy 

 being applied, the work of destruction begins. If a 

 tooth is only partly deficient, no matter whether it be 

 from fracture, caries, or arrestation of growth, it is 

 gradually destroyed by the opposite tooth. AVhen it 

 is the first upper grinder that is deficient, the first 

 lower acts on the palatine vault like a battering-ram. 

 'I have seen/ says Solleysel (1669), *a mule that had a 

 lower grinder of extreme length, the upper tooth being 

 absent. -The palate was pierced to the thickness of a 



* The italicized words are mine. 0. 



