124 THE SENSORIAL FUNCTION. 



the horse, and enables that organ readily to revolve by the slightest contraction 

 of the muscles. By the absorption of this fatty matter in sickness or old age, 

 the eye is not only to a certain degree sunk in the orbit, but the roof of the orbit 

 posterior to the frontal bone, being deprived of its support, is considerably 

 depressed. Our work shall not be disgraced by any farther reference to the 

 rascally contrivance by which this indication of age is in some degree removed. 



In front the eye is supported and covered by the lids, which closing rapidly, 

 protect it from many an injury that threatens supply it with that moisture 

 which is necessary to preserve its transparency in the momentary act of 

 closing give a certain and sufficient respite to a delicate organ, which would 

 otherwise be fatigued and worn out by the constant glare of day defend it when 

 the eye labours under inflammation from the stimulus of light, and, gradually 

 drooping, permit the animal to enjoy that repose which nature requires. 



Extending round both lids, and, it may be almost said, having neither origin 

 nor insertion, is a muscle called the orbicularis, or circular muscle. Its office is 

 to close the lids in the act of winking or otherwise, but only while the animal 

 is awake. When he sleeps, this is effected by another and very ingenious 

 mechanism. The natural state of the eyelids is that of being closed ; and they 

 are kept open by the energy of the muscles whose office it is to raise the upper 

 lid. As sleep steals upon the animal, these muscles cease to act^ and the lids 

 close by the inherent elasticity of the membrane of which they are composed. 



The skin of the lid is, like that of the ear, exceedingly fine, in order to pre- 

 vent unnecessary weight and pressure on such a part, and to give more easy and 

 extensive motion. The lids close accurately when drawn over the eye, and this 

 is effected by a little strip of cartilage at the edge of each of them, which may 

 be easily felt with the finger, and preserves them in a hoop-like form, and 

 adapts them closely to the eye and to each other. The lower cartilage, how- 

 ever, does not present, towards the inner corner of the eye, the whole of its flat 

 surface to the upper, but it evidently slopes inward, and only the outer edge of 

 the under lid touches the upper. By this means, a little gutter is formed, 

 through which the superfluous moisture of the eye flows to the inner corner, 

 where there is a canal to convey it away. By this contrivance it neither accu- 

 mulates in the eye, nor unpleasantly runs down the cheek. 



Along the edges of the lids are placed numerous little hollows, which can be 

 plainly distinguished even in the living horse by slightly turning down the lid. 

 These are the openings into numerous small cells containing a thick and unctuous 

 fluid, by means of which the eyes are more accurately closed, and the edges of 

 the lids defended from the acrimony of the tears. 



The horse has no eyebrows, and the eyelashes are very peculiarly arranged. 

 The rows of hair are longest and most numerous on the upper lid, and especially 

 towards the outer or temporal corner, because the light comes from above; and, 

 as the animal stands, particularly when he is grazing, and from the lateral 

 situation of his eyes, the greater portion of the ligbt, and the attacks of insects, 

 and the rolling down of moisture, would chiefly be from the outside or temples. 

 Towards the inner corner of the upper lid there is little or no eyelash, because 

 there is no probable danger or nuisance in that direction. Only n small quan- 

 tity of light can enter from below, and therefore the lashes are thin and short ; 

 but as, in the act of grazing, insects may more readily climb up and be trouble- 

 some to the eye, towards the inner angle, there the principal or only hair is 

 found on the lower lid. These apparently trifling circumstances will not be 

 overlooked by the careful observer. 



They who are unacquainted with the absurdities of stable management, or 

 who have not carefully examined the abuses that may exist in their own 

 establishments, can scarcely believe the foolish and cruel practices of some 



