322 TOLL EVIL. 



shy at almost every object which he encounters, in consequence 

 of his sight being but partially restored by the operation. 



-WALL EYE. 



This peculiar appearance of the iris in some horses is not the 

 result of disease, but is occasioned by the absence of what is 

 called the pigment, which gives color to the eye. This pigment 

 is secreted upon the inside of the iris, and where it does not 

 exist, the iris, or that part of the eye which surrounds the 

 pupil (so called from its brilliancy) remains white. Percival 

 says : " It is a remarkable fact that this variety of hue in the 

 iris corresponds with the color of the hair ; bay and chestnut 

 horses have hazel eyes ; brown horses have brownish eyes ; and 

 very dark brown or black horses, eyes of a still darker, dusky 

 brown shade. This curious relation is still more observable 

 in human beings; the diversity of colors and hues in their 

 irides being infinitely greater than any thing we behold among 

 any one species of animals. Cream-colored and milk-white 

 horses have wall eyes, and albinos have red eyes ; in both which 

 instances the iris is said to be destitute of any coloring matter 

 whatever." 



MISCELLANEOUS DISEASES. 



POLL EVIL. 



This disease arises from blows inflicted upon the poll, or 

 back part of the head, of animals whose blood is impure, or in 

 a morbid condition. Horses going in or out of stables with 



