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sac, into ^yllicll the laclirymal ducts open, may fail to discharge its 

 contents b}' reason of constriction or closure of the duct leading to the 

 nose, and it then forms a rounded swelling beneath the inner angle 

 of the eye. The duct leading from the sac to the nose may be com- 

 pressed or obliterated by fractures of the bones of the face, and in 

 disease of these bones (osteo-sarcoma, so-called osteoijorosis, diseased 

 teeth, glanders of the nasal sinuses, abscess of the same cavities). 



The narrowed or obstructed ducts may be made pervious by a fine 

 silver probe passed down to the lachrymal sac, and anj" existing 

 inflammation of the passages may be counteracted by the use of 

 steaming mashes of wheat bran, by fomentatioiis or wet cloths over 

 the face, and even by the use of astringent eye washes and the injec- 

 tion of similar liquids into the lachrymal canal from its nasal opening. 

 The ordinary eye wash may be used for this purpose, or it jnny be 

 injected after dilution to half its strength. The fractures and dis- 

 eases of the bones and teeth must be treated according to their special 

 demands when, if the canal is still left ijervious, it may be again 

 rendered useful. 



EXTERNAL OPHTHALMIA — COX JUNCTIVITIS. 



In inflammation of the outer parts of the eye ball the exposed vas- 

 cular and sensitive mucous membrane (conjunctiva) which covers the 

 ball, the eyelids, the haw, and the lachrymal apparatus, is usually the 

 most deeply involved, yet adjacent parts are more or less implicated, 

 and when disease is concentrated on these contiguous iDarts it consti- 

 tutes a phase of external ox)hthalmia which demands a special notice. 

 These have accordingly been alreadj^ treated of. 



The causes of external ophthalmia are mainly those that act locally — 

 blovrs with whips, clubs, and twigs, the presence of foreign bodies 

 like hay-seed, chaff, dust, lime, sand, snuff, pollen of plants, flies 

 attracted by the brilliancy of the eye, wounds of the bridle, the migra- 

 tion of the scabies (mange) insect into the eye, smoke, ammonia rising 

 from the excretions, irritant emanations from drying marshes, etc. 

 A very dry air is alleged to act injuriously by drying the eye as well 

 as by favoring the production of irritant dust ; and the undue exposure 

 to bright sunshine through a window in front of the stall, or to the 

 reflection from snow or water, is undoubtedly injurious. The unpro- 

 tected exposure of the eyes to sunshine through the use of a very 

 short overdraw check is to be condemned, and the keeping of the 

 horse in a very dark stall from which it is liabitually led into the 

 glare of full sunlight, intensified by reflection from snow or white 

 limestone dust, must be set down among the locally acting causes. 

 But exposure to cold and wet, to rain and snow storms, to cold 

 draughts and wet lairs must also be accepted as causes of conjuncti- 

 vitis, the general disorder which they produce affecting the eye, if 

 that happens to be the weakest and most susceptible organ of the 



