88 EYES. 



purpose of carrying off any superfluous moisture or 

 tears into the nose: the eye has four coats or mem- 

 branes, and three humours ; the first membrane is called 

 tunika adnata, and covers all that part of the eye that 

 in a man appears white, but in a horse is variegated 

 with streaks and spots of brown, and being reflected 

 back, lines the inside of the eyelids, and by that inver- 

 sion becomes the means to prevent motes, dust, small 

 flies, or any extraneous matter getting behind the eye- 

 ball into the orbit, which would be extremely danger- 

 ous : this coat is full of blood vessels, which appear in 

 little red streaks on the human eye when inflamed, 

 and when there is but little white in the eyes of 

 horses, they appear fiery, and the eyelids, when 

 opened and turned back, look red : the second coat has 

 its forepart very strong and transparent, like horn, 

 and is therefore called the cornea ; and the other part, 

 which is opaque and dark, is called the schlerotis : 

 under the cornea lies the iris, which in a horse inclines 

 to cinnamon colour : the middle of this membrane, 

 or coat, is perforated for the admission of the rays 

 of light, and is called the pupil : under the iris lies 

 the processes ciliares, which go off in little rays, and 

 in a sound eye are plainly to be seen. As often 

 as these processes contract, they dilate the pupil, 

 which may always be observed in places where the 

 light is small ; but in a strong light, the circular fibres 

 of the iris act as a sphincter muscle, and lessen the size 

 of the pupil ; and therefore a dilated and wide pupil, in 

 a strong light, is generally an evidence of a bad eye. 

 Under the schlerotis lies the choroides, which is the 

 third coat of the eye : in men it is of a dusky brown, 

 but in horses the greater part of this coat is white; 

 which enables them to see bodies of all colours better 

 than men m the night, as white reflects all colours. 



