55 



of cutting it off iniist, therefore, be sufficiently 

 obvious. 



The external surface of the eye, in its healthy 

 state, is thoroughly transparent. The centre 

 of it, which is called the pupil, or sight, is 

 generally of a dark indefinite colour. The 

 pupil has the property of contracting or dilating 

 itself, in proportion to the strength of light 

 which enters tlie eye. 



To examine a horse's eyes with accuracy, he 

 should be led to the stable door, with his head 

 facing the light. In this situation the pupils 

 of both eyes should appear exactly of the same 

 size. As he advances more into the light, the 

 pupils should contract ; but if either of them 

 does not contract, the horse is certainly blind 

 of that C3^e. 



This species of blindness arises from a palsy 

 in the optic nerve, and is so little perceptible, 

 that many good judges have bought horses of 

 this description, M'ithout knowing that they 

 were blind of one eye. 



Another cause of blindness, more perceptible, 

 but equally incurable, arises from an opacity of 

 the chrystalline lens, constituting a cataract; 

 or, to use a more familiar' term, a whiteness 

 over the pupil or sight of the eye. This general 

 whiteness over the sight, however, seldom 

 comes on all at once. It commonly begins 



