254 DISEASES OF THE HOESE. 



bodies, such as sand, dust, and chaff, or other irritants have fallen on 

 the eyeball or eyelids, it is similarly projected to push them off, their 

 expulsion being further favored by a profuse flow of tears. 



This is seen, to a lesser extent, in all painful inflammations of the 

 eye, and to a very marked degree in lockjaw, when the spasm of the ^ 

 muscles of the eyeball draws the latter deeply into the orbit and pro- 

 jects forward the masses of fat and the cartilage. The brutal practice 

 of cutting off this apparatus, whenever it is projected, necessitates 

 this explanation which, it is hoped, may save to many a faithful serv- 

 ant a most valuable appendage. That the cartilage and membrane 

 may become the seat of disease is undeniable, but so long as its edge 

 is thin and even, and its surface smooth and regular, the mere fact of 

 its projection over a portion or the whole of the eyeball is no evidence 

 of disease in its substance, nor any warrant for its removal. It is 

 usually but the evidence of the presence of some pain in another part 

 of the eye, which the suffering animal endeavors to assuage by the use 

 of this beneficent provision. For the diseases of the cartilage itself, 

 see " Encephaloid cancer." 



LACHRYMAL APPARATUS. 



This consists, first, of a gland for the secretion of the tears, and, 

 second, of a series of canals for the conveyance of the superfluous 

 tears into the cavity of the nose. 



The gland is situated above the outer part of the eyeball, and the 

 tears which have flowed over the eye and reached the inner angle are 

 there directed by a small conical papilla (lachrymal caruncle) into 

 two minute orifices, and thence by two ducts (lachrymal) to a small 

 pouch (lachrymal sac) from which a canal leads through the bones 

 of the face into the nose. This opens in the lower part of the nose on 

 the floor of the passage and a little outside the line, of union of the 

 skin which lines the false nostril with the mucous membrane of the 

 nose. In the ass and mule this opening is situated on the roof instead 

 of the floor of the nose, but still close to the external opening. 



EXAMINATION OF THE EYE. 



To avoid unnecessary repetition the following general directions are 

 given for the examination of the eye : The eye, and to a certain extent 

 the mucous membrane lining the eyelids, may be exposed to view 

 by gently parting the eyelids with the thumb and forefinger pressed 

 on the middle of the respective lids. The pressure, it is true, causes 

 the protrusion of the haw oyer a portion of the lower and inner part 

 of the eye, but by gentleness and careful graduation of the pressure 

 this may be kept within bounds, and oftentimes even the interior of 

 the eye can be seen. As a rule it is best to use the right hand for the 

 left eye, and the left hand for the right, the finger in each case being 



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