348 OUR HUMBLE HELPERS 



is brought into play. Need I go over all this again ! ' ' 



"No, Uncle, " replied Jules; "we all remember 

 how ivory wears away by degrees, but the folds of 

 enamel cap this softer substance and keep the molars 

 in a proper condition for crushing the food. ' ' 



' ' Then I will continue by showing you how by ex- 

 amining a horse's incisors we may learn the animal's 

 age. These incisors are six in number in each jaw. 

 They are accompanied in the upper and often also 

 in the lower jaw by two small canine teeth having 

 the shape of pointed nipples. Beyond these, and 

 until the row of molars begins, the jaw is toothless, 

 and this part is called the bar. ' ' 



"I know," broke in Louis; "it is in the bar that 

 the bit is placed with which the horse is guided. " 



"Let us return to the incisors. The two in the 

 middle of the jaw are called the first or central inci- 

 sors ; the next two, one on the right and the other on 

 the left of the first ones, are called the second inci- 

 sors ; finally, the two last, one on each side, are called 

 the third incisors. Remember these names; they 

 will save us the trouble of roundabout expressions. 



"A few days after birth the central incisors show 

 themselves in each of the foal's jaws. In one or 

 two months the second incisors appear, and in six 

 or eight months the third incisors pierce the gum. 

 These are the first or milk teeth, as they are called. 

 When the animal is between two and a half and three 

 years old they fall out and are replaced by the sec- 

 ond teeth, which make their appearance in the same 

 order as the preceding ones: first the central inci- 



