260 



PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



These changes are also indicated in the following diagrams from the 

 " Encyclopadie der gessammten Thierheilkunde " (Fig. 105). 



2 Months. 

 (Milk-Teeth.) 



Years. 

 (2 Broad Incisors) 



% Years. 

 (4 Broad Incisors.) 



2M Years. 

 (6 Broad Incisors.) 



4 Years. 

 (8 Broad Incisors. ) 



Over 7 Years. 

 (8 Broad Incisors.) 



FIG. 105. CHANGES FROM AGE IN THE INCISOR TEETH OF THE SHEEP. ( Wilckcns. ) 



Teeth of Carnivora. All the carnivora have simple teeth ; i.e., 

 covered entirely over the crown by white enamel. There are three pairs 

 of incisors, one pair of canines, and a certain number of molars. It is 

 the last premolars, or the first true molars, which are emplo^yed in chew- 

 ing flesh; they are prominent and sharp. Behind these, especially in the 

 dog, the teeth are armed with round tubercles on their surface, destined 

 for crushing or grinding action, and in breaking bones or gnawing long- 

 grass the dog may be seen -to push the substance between these back 

 molar teeth. 



Dentition in Dog. 



6 1-1 6-6 



Incisors - ; canines ; molars = 42. 



6 1-1 7-7 



The dog is born with his eyes shut ; they open on the tenth or fifteenth 

 day after birth. The whole of the milk-teeth are usually cut then, or 

 very shortly after. Between two and four months the central incisors 

 and often even the middle ones of both upper and lower jaws drop out, 

 and speedily the whole of the permanent teeth are fully developed, so 

 as to complete the mouth by eight months. 



The inferior incisors begin to wear by fifteen months. Fig. 106 

 shows the milk-teeth in a puppy two or three months old ; Fig. 107 in a 

 year-old dog. At eighteen months, or two 3 r ears, the inferior central 

 incisors are much worn, and between two and three years the middle 

 ones also (Fig. 108) ; the worn incisors bear a striking contrast to the 



