144 THE PATHOLOGY OF THE TE 



finger, which caused the animal great difficulty when 

 he drank.' 



"4- Caries of the Teeth. The grinder teeth of horses 

 are more frequently affected with a profound alter- 

 ation of their substance than is generally believed. 

 The disease is called Caries; it may not, however, be 

 strictly analogous to caries of the bones, for the bones 

 are vascular, while the teeth have neither vessels nor 

 nerves. Caries of the bones implies an active labor, in 

 which the vascular apparatus plays an important part. 

 It is a phenomenon of interstitial suppuration, under 

 the influence of the inflammation which has set the 

 capillary system of the organ in play. In explaining 

 caries of the teeth, however, we cannot invoke the 

 aid of inflammation and the modifications it induces 

 in the tissues it attacks ; nor can we say that inflam- 

 mation implies an active circulatory movement, an 

 afflux of liquid, an alteration, nervous derangement, 

 &c. If the teeth are living, the laws which govern 

 their vitality are entirely unknown to us.* How, then, 

 penetrate into the secrets of the alterations which they 

 undergo, when the conditions of their normal existence 

 are enveloped in obscurity? Neither is it possible to 

 resolve the question as to the essence of the affection 

 designated by the name of caries. Therefore we design 

 to make known only the different modes of expression 

 relative to it. 



" Caries usually attacks the dentine of the crown of 

 the teeth, between two folds of enamel. The dentine 

 becomes of a brownish or blackish color, and dissemi- 



* It should be borne in mind that the above views were enun- 

 ciated more than a third of a century ago. The gentlemen 

 probably say too much. Compare with Dr. Hayes's views as 

 recorded on page xxii. 



