THE ANATOMY OF THE HORSE. 55 



CHAPTER XIV. 



THE EYE. 



THE eye is the chief organ of sigiit, and is situated in the 

 orbital fossa, which was mentioned in the bones of the 

 head. It is chiefly made up of several coats around the 

 outside and in the centre, by the humours of the eye. On the inner 

 side of the coats is a thin membrane called the retina, which 

 contains the branches of the optic nerve, this receives the re- 

 flections of objects as they pass through the humours of the eye 

 and they pass along the optic nerve to the brain. The oblong 

 openings seen in the middle of the eye are known as the pupils 

 of the eye. In leading a horse out of a dark stable into the 

 light and watching the pupils of the eye, they will be noticed 

 to get smaller, then on returning it to the stable the pupils 

 will be noticed to dilate or get larger, thus it is seen the 

 pupil does not always remain the same size. The chief use 

 of the pupil is to gauge the sight. At the back part of the eye 

 are several muscles which are attached from around the eye to the 

 bones in the fossa, the use of these muscles are to move the eye 

 and assist in holding it to its place. Around the front part of the 

 eye are two movable curtains, one above and the other below, 

 these are called the eyelids, the use of which are to open and close 

 the eye, and also to potect it from injuries. Around the free border 

 of the eyelids are what is known as the eyelashes, the use of 

 which are to keep foreign substances from falling into the eye. 

 Situated in the inner angle of the eye is what is known as the haw 

 of the eye, this membrane also helps to protect the eye. In the 

 corner of this angle is a small duct or opening, where the tears of 

 the eye pass down through into the nasal tubes, where it is carried 

 down through the bones of the head and emptied into the under 

 part of the nostril or nose. A small gland is situated on the 

 upper part of the eye, secreting the tears which lubricate the eye. 

 The color of the eye is generally brown, but in some cases it is 

 white and receives the name of a walled eye. 



