414 THE COMPLETE GRAZIER, BOOK in. 



put by an adult to the dentist, as to whether a tooth just extracted will 

 "grow again," is quite superfluous. In order to understand the names 

 given to teeth, let the reader, if he has a tolerably sound set, look into 

 his own mouth by means of a mirror. In the middle of the arcade he 

 will see four biting teeth, two on either side of the middle line, above 

 and below. These are the incisors. Flanking each of these four pairs, 

 on the outside, is a conspicuous pointed tooth, the canine tooth, so that 

 there are four canine teeth altogether. These are the " tushes " in the 

 horse, and the " tusks " in the boar. Beyond, on each side, above and 

 below, are five other teeth, the grinding teeth, or molars. They are 

 characterised by the flat extended surfaces that meet in opposition, and 

 serve to masticate the food. It is obvious that of these there are 

 normally twenty, though as the last molar in the row, the "wisdom 

 tooth," does not invariably come through, there may be as few as six- 

 teen molars in the mouth of an adult man or woman. Of the thirty-two 

 teeth which have been enumerated, it is seen, then, that eight are 

 incisors, four are canines, and twenty are molars. But, of these, all 

 the incisors, all the canines, and the first two molars on each side, above 

 and below, are replaced, whilst the last three molars on each side above 

 and below, come into position once for all. Hence the temporary or 

 milk dentition of man comprises twenty teeth eight incisors, four 

 canines, and eight premolars, as the front molars are termed. This 

 may be denoted by the following " dental formula " : 



22 11 22 



d.i. d.c. d.m. = 20 



22 11 22 



which means that there are two deciduous incisors on either side of the 

 middle line, above and below, similarly there is one canine, and in like 

 way there are two deciduous molars. All these give place to suc- 

 cessors, and the permanent dentition, or adult dental formula, of 

 man is 



11 22 3-3 

 c. p.m. m. = 32 ; 



22 11 22 33 



where "p.m." denotes pre-molars (or successors of deciduous molars), 

 and " m." molars. 



It will now be easy to understand the dentition of the ox and the 

 sheep, in both of which animals the dental formulae are practically 

 identical. The milk detention is 



oo 33 



d.i. p.m. = 20 



4-4 33 



The permanent detention is 



oo 33 38 



L p.m. m. = 32 



44 33 33 



