THE STRUCTURE OF THE TEETH 61 



than if bred as common stock ? Examples of this forward 

 growth of the teeth have occurred, whereby the age might 

 be doubted. We have also seen the reverse of this, though 

 a rare occurrence, where the colt had arrived at the age of 

 three, and not moved a tooth. These variations are 

 commonly considered the result of early or late foaling, 

 but as likely to occur from peculiarity of constitution. 



The horse has twelve incisors or nipping teeth in the 

 upper and lower jaws, opposed |- ; four tushes or tearing 

 teeth, placed ■}, y, on each side of the cutting teeth ; and six 

 molars or grinding teeth, in the branch of each jaw above 

 and below. The mare not having the tushes or canine 

 teeth, has but thirty-six, while the full-mouthed horse has 

 forty. 



In ordinary cases the teeth will be found a sufficient 

 criterion of the animal's age, if examined by one who can 

 properly read their criteria. 



With these preliminary remarks, we shall proceed to a 

 description of the teeth — their structure, growth, and 

 changes, as auxiliary to the determining of the age of the 

 animal by their inspection. 



THE STBUCTURE OF TEE TEETH. 



Each tooth is divided into three parts for the purpose of 

 description, the crown or tahle^ which is its upper surface ; 

 the nech, which is the part surmounted by gum, and where 

 it usually begins to diminish in size ; and the fang^ or root, 

 which is the part out of sight in the alveolar cavity. 



The teeth are contained in the upper and lower jaw- 

 bones (or maxillaries), in small bony cups or holes, each 

 tooth being contained in a separate cavity, called 

 collectively alveolar cavities ; and in the molars, where 

 there are more than one fang, each root has its separate 

 cup, with bony matter intervening between itself and other 

 fangs. 



The teeth are organised bodies, as is shown by the 

 absorption of their substance, in case of the roots of the 

 temporary teeth ; their sensibility to pain upon application 

 of extreme heat, cold, or strong acids ; their growth and 

 changes of form ; and their resistance of decay, while 

 possessed of vitality. They possess, for their supply and 

 Bustainment, arteries, veins, and nerves. 



