48 THE TEMPORARY 



eral development, the foal has no teeth at birth, Na- 

 ture providing a membrane-like cover for the incisors 

 as well as the hoofs. In two or three days, however, 

 the molars are all cut. The incisors are cut in pairs, 

 two above and two below. The first pair protrude in 

 from three to eight days, and attain their growth in 

 about two months. The second pair are cut when the 

 foal is five or six weeks old. They also attain their 

 growth in about two months. The time of cutting the 

 third pair varies. In some foals they appear as early 

 as the sixth month ; in others as late as the ninth. 

 They attain their growth in about three months.* 



The milk teeth are smaller and whiter and have 

 more distinct necks than the permanent. Their shin- 

 ing, milky-white color, M. Chauveau says, is due to 

 the thinness or absence of the cement, their crowns 

 being finely striated (not cannular) on the anterior 

 face, and their growth, unlike the permanent teeth, 

 ceasing when they begin to be used, f 



* Rousseau assigns from the seventh to the tenth month as the 

 period of the first dentition. The deciduous incisors have thinner 

 and more trenchant crowns than the permanent. Owen. 



f The disintegration of the deciduous teetli by the processes of 

 shedding and replacement is one reason for their growth " ceasing 

 when they begin to be used ; " but continuous growth is apparently 

 contrary to their nature. When naturally shed, the roots and most 

 of the crowns are absorbed, that is, resolved into their original ele- 

 ments, by the contiguous tissues concerned in the processes named. 

 These natural tooth-elements nourish the permanent teeth, and in 

 the case of the horse may account to some extent for their continu- 

 ous growth. The evil of extracting healthy deciduous teeth is there- 

 fore obvious. Abbott speaks of " the melting process of the cemen- 

 tum and dentine of deciduous teeth," and of the "bay-like excava- 

 tions " of the enamel. He also says : " It has never been doubted that 

 a persistent, though gradual, irritation causes the absorption. This 

 irritation is due to the growth and progress of the permanent teeth." 



