72 THE ANATOMY OF THE HORSE. 



grinding, and are placed on either side of the jaws, rather 

 to the back of the mcuth. The same substances enter into 

 their composition as form the nippers. Thus the bone, being- 

 yielding, gives way under the grinding process, and by its 

 action becomes indented. The crusta petrosa, being soft, 

 also is carried off, save where it clings to the side, as a pro- 

 tector. The enamel being very hard, and between both, 

 projects above either, and thus keeps the surface sharp, or 

 admirably adapted to perform its office. 



Six molars are placed close together, on either side of 

 each jaw ; then there is a vacant space, then a tush on 

 either side of each jaw ; then another space, and then six 

 incisors ; thus the teeth of the horse do not, like the 

 teeth of man, form a continuous line, but occur as it were 

 in patches, and in this manner the teeth of the great 

 majority of the brute creation are placed in their heads. 



The use of the tushes Mr. Percivall, in our opinion, 

 rightly conjectures to be as weapons of offence. Mr. Per- 

 civall's judgment is, however, much contested by some 

 writers, who appeal to the worn state of the tushes in age 

 as proof conclusive of the unsoundness of that author's 

 decision. But the wear is consequent on the bit introduced 

 into the horse's mouth, which the animal could hardly be 

 supposed to possess, in any state of nature they may please 

 to imagine. Did these gentleman objectors ever observe 

 the tushes in a stallion kept for service ? If so, they must 

 at once relinquish their ideas of these teeth not being long 

 enough to be used as weapons of offence. The horses kept 

 for this purpose scarcely ever have a bit put into their 

 mouths, and the tushes become of exceeding length. The 

 animal, as it at present comes into our possession, may not 

 use the tushes as weapons of offence, but then it has been 

 so domesticated, that we need not wonder if very many of its 

 habits are entirely forgotten or abandoned. 



It now becomes our duty to speak of the manner in 

 which the temporary teeth are removed, and the permanent 

 projected into the mouth. This takes place by absorption. 

 The harder substance, in the living body, seems to yield and 

 be governed by the softer : thus the bones of the skull are 

 regulated, as to their size and dimensions, by the magnitude 

 of the brain ; the extent of the ribs is subservient to the 



