6 AGE OF THE DOMESTIC ANIMALS. 



unable to supply the tissues with nutritive matter equal to that 

 which is destroyed and thrown off, and the animal emaciates. 

 The functions slow ; the senses are diminished and finally 

 become extinct. 



As the determination of age, in all of the domestic animals, 

 depends primarily on the alterations which take place in their 

 teeth, and, secondarily, upon other signs and changes, the sub- 

 ject will be taken up in regular order : First, the study of the 

 dentition of the animal, the number and structure of its teeth, 

 and the manner of eruption and the alterations which they 

 undergo by use ; then the various other organs which undergo 

 characteristic changes Avith age will be described, — the horns 

 and other epidermic products, the alterations of form and of 

 expression. 



The species of animal will be taken up according to its 

 importance and value as an article of commerce. 



