140 VETERINART DENTAL SURGERT. 



tice. If we extract a tooth from a horse eight years 

 old, and compare it with a corresponding tooth 

 that has been extracted from a horse 

 sixteen or eighteen years old, there 

 will be a considerable difference in 

 their length in favor of the younger 

 tooth. In aged animals there often 

 remain only the roots of the teeth. 

 These roots are very short and easily 

 removed; had the growth offset the 

 wear this would not have been the 

 result. 



* " It is not until the tooth begins 

 to be pushed from the alveolus and 

 the crown to become worn that its 

 fangs are formed; these are at first 



tooVS'ha! hollow and afterwards filled, as 



been extracted. we n as the cav i ty o f the tooth, by 



The table surface 



shows the irregu- the formation of a new quantity of 



lar wear to which 



it has been sub- dentine. .From this time the fang 



ceases to grow; but the tooth con- 

 stantly projected beyond the alveolar cavity, allows 

 the walls which enclose it to contract, so that in 

 extreme old age it happens that the shaft com- 

 pletely worn away, instead of the tooth, leaves 

 several stumps formed by the fangs." 



j " The permanent teeth are thrust up from the 



* Chauveau, Comp. Anat. Page 354. tSame, Page 349. 



