194 CONFESSIONS OF A HOBSE DEALER. 



some obstacle, when there is actually nothing to impede 

 his free progression. 



But, notwithstanding that these symptoms would be 

 sufficient to create suspicion, there are other causes 

 (besides imperfect vision) by which the same, or similar 

 symptoms, would appear in horses. .For instance, if a 

 horse with the most perfect pair of eyes were led from 

 a dark stable into the blazing sunshine, the sudden 

 contraction of the pupil of his eye would render it im- 

 possible, for a few moments, for him to see but very in- 

 distinctly; hence would arise the same symptoms of 

 uncertainty in his movements, until the pupil becomes 

 steady after the sudden contraction. 



The dilation and contraction of the pupil of the 

 horse's eye furnishes the principal means of ascertaining 

 whether the blindness exists in one eye or both, as this 

 pupil varies in size, according to the degree of light 

 which is brought to bear upon it. In a dark stable the 

 pupil is expanded, so that a greater proportion of light 

 falls upon the cornea ; but if the horse is led to the 

 door of the stable, the pupil will contract, so as to ex- 

 clude more light than could be endured, and if suddenly 

 exposed to the sun, the aperture will be all but closed ; 

 therefore the novice should carefully notice these varia- 

 tions in the pupil, whether they contract or expand 

 equally by the increase or decrease of the light which 

 he may readily perceive by advancing the horse's head 

 to the open door or window of the stable, and backing 

 him again into the darkness, until he is satisfied as 



