OF FARRIERY. 



81 



The next muscle is the abductor, which arises 

 from the posterior part of the orbit, and is 

 inserted into the anterior part of the sclerotic 

 coat on the outside ; this muscle directs the 

 eye from the nose, and unlike the levators, 

 these muscles cannot act together, for one eye 

 being turned from the nose, the other is 

 directed to the nose by another muscle ; the 

 intention of this is obvious, that in cases of 

 alarm, both eyes should be directed to the 

 same object, one by the abductor, and 

 the other by the adductor. The depressor 

 occuli arises from the posterior part of the 

 orbit, and is inserted into the inferior part of 

 tlie sclerotic coat. The adductor has the 

 same origin, and is inserted into the sclerotic 

 coat towards the inner cayithus. All these 

 muscles acting together, have the power of 

 drawing the eye into the orbit; but their 

 action is inconsiderable. 



The oblique muscles, which are two, one of 

 which arises from the inferior part of the orbit, 

 and is inserted into the sclerotic coat below, 

 the other called the trochliaris, arises from 

 the same, and going through a pulley-like 

 adaptation, is inserted into the anterior part of 

 the sclerotic coat, and thus draws the eye 

 forward. Their chief use is to act in opposition 

 to the straight muscles, by drawing the eye 

 forward. 



The retractor occuli arises from the supe- 

 rior part of the orbit, surrounds the optic nerve, 

 but is separated from it by adeps [i. e. fat] ; and 

 that the fibres may not affect the nerve, they 

 are not attached to the sclerotic coat, where 

 the nerve emerges. This muscle performs 

 two functions : I will just mention here how you 

 may distinguish the inner and outer canthiis ; 

 when the eyes are separated from the body, 

 it is the broad side which forms the inner 



canthus, over which the haio plays. I may 

 here allude to the formation in birds, which is 

 a little similar to the haic, called the membrana 

 nictitans, a semi-transparent membrane, 

 having a muscle and a tendon. In the Horse 

 this is cartilage edged with black, at the 

 anterior part fastened to the conjunctiva by the 

 cellular membrane, and if you attempt to pass 

 your 6nger between the eye and the haw, you 

 are prevented by the conjunctiva, showing that 

 the conjunctiva is a reflected membrane over 

 the cellular attachment. The haic is divided 

 into two parts ; the anterior part is convex on 

 the outer surface, concave on the inner, to fit 

 the convexity of the eye ; the haiv acts as a kind 

 of shield, but not being sufficient to cover the 

 whole orb, whilst in its natural situation, the 

 retractor muscle acts first, by which means 

 the ball of the eye presses upon the adeps, 

 and the haw, in consequence, is forced over the 

 eye, showing it has no movement of its own, 

 but is dependent on the retractor muscle, thus 

 performing its functions by moving apart, 

 to which it is least attached. 



LACHRYMAL GLANDS. 



In noticing the lachrymal glands placed 

 above the levator palpebree, laying close to the 

 sclerotic coat, white and large, and through 

 being of a white colour, consequently, not pos- 

 sessing much blood, its secretion is large, as 

 may be proved by its duct, which secretion is 

 evidently regulated by circumstances. These 

 ducts pierce the conjunctiva at the upper and 

 outer part, and thus moisten the eye. 



THE EYE-LIDS. 



The eye-lids in the Horse, must claim a 

 little attention, the peculiarity of them, is, the 

 bottom one has no lashes, but the upper one 



