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be destroyed or their permanent presence made known by 

 the immovable iris and unchangeable form of the pupil. The 

 iris, when attached to the capsule of the lens or to the cor- 

 nea, may appear rough on its outer surface and its pupillary 

 border is more or less irregular. The ragged, irregular 

 border of the pupil should not be mistaken for the large 

 brown "soot balls" that appear so frequently along the upper 

 and lower parts of the pupillary border of the iris. The 

 movements of the iris should also be watched when the ani- 

 mal is taken from the sunlight into the barn, or from the 

 dark stall into the sunshine. If the pupil contracts regu- 

 larly in bright light and expands regularly in partial dark- 

 ness, the action of the iris is normal. But should the pupil 

 remain greatly expanded under all conditions of light and 

 darkness, one would suspect partial or total amaurosis. If 

 the pupil remains partiall}- or greatly contracted under all 

 conditions of light and darkness, one should suspect adhe- 

 sion of the iris to the capsule of the lens. 



The pupillary reflex or color of the pupil is the reflection 

 of light from the retina and the choroid. The normal color 

 of the pupil varies with the variations in its size or in its 

 degrees of expansion or contraction ; its color also changes 

 with the variations in the light. By great expansion of the 

 pupil it appears ])lue-green ; by medium expansion it appears 

 blue-black; by great contraction it appears black. The 

 color of the pupil in amaurosis is generally lighter, more 

 clear and glassy than in the normal eye. When the pupil is 

 small atropine should be used to produce maximum expan- 

 sion. Or, the animal may be taken into a moderately dark 

 stall where the color of the light reflected from the upper 

 part of the retina and choroid will be green, and that re- 

 flected from the optic papilla (spot where the optic nerve 

 enters the eye ball) will appear light red. This light red 

 color is very distinct in carnivorous animals. 



Cloudiness of the lens or the vitreous humor changes the 

 color of the pupil according to the intensity of the cloudiness. 

 Total cataract gives the pupil a gray, a white or a whitish- 



