1 82 MANUAL OF MODERN FARRIERY 



In the horse it is of an oblong form (see Plate 

 III, fig. 4). It is variable in size, depending upon 

 the intensity of the light in which it is viewed. In 

 the open air it will be much contracted, so as to 

 prevent too large a quantity of light being thrown 

 upon the retina, as it is painful and injurious to that 

 object to receive too great a portion of it, as well as 

 prejudicial to vision ; while in a dark stable it 

 expands, in consequence of a deficient portion of 

 lio^ht reachincr the retina. 



This contraction and expansion of the pupil is 

 of much service in enabling purchasers to judge of 

 the state of the horse's sight. There is a description 

 of blindness, in which the crystalline lens and cornea 

 continue quite transparent, but the retina of the eye 

 is palsied, and consequently not affected by light ; 

 so that the pupils are hardly if at all altered by a 

 change from light to darkness, or vice versa. In 

 purchasing a horse, the size of both pupils should 

 be strictly observed, to see that they both expand 

 and contract to the same extent by the change of 

 light. The hand ought to be held over the eyes for 

 a short time, and then notice if both pupils expand 

 alike, when removed. 



Suspended from the upper edge of the pupil of 

 the eye two or three black bodies may be discovered 

 on close inspection, the size of millet-seeds. When 

 the horse is suddenly brought into an intense light, 

 the pupil suddenly contracts ; these little globes are 

 pressed out from between the edges of the iris, and 

 an equal number, but of much smaller size, are 

 attached to the lower edge of the iris. Their use, 

 probably, is to intercept portions of light which would 

 be injurious to the eye. But their chief function is 

 called into action while grazing, and perform the 



