MANUAL OF EQUINE MEDICINE. 



of natural selection, has been of very great importance in 

 the establishment of the various breeds of horses. 



It is indeed remarkable how the forms of horses have 

 been modified by the various conditions of life. As an 

 example, it is well-known how horses living in mountainous 

 districts, or small islands, become reduced in size from 

 deficient supply and want of variety of food. 



