348 HORSE, SWINE AND POULTRY DISEASES 



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 OP 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 over a portion of the lower and inner 

 part of the eye, but by gentleness and careful graduation of the pres- 

 sure this may be kept within bounds, and oftentimes even the inte- 

 rior 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 eye, the finger in each 

 case being pressed on the upper lid while the thumb depresses the 

 lower one. In cases in which it is desirable to examine the inner side 

 of the eyelid further than is possible by the above means, the upper 

 lid may be drawn down by the eyelashes with the one hand and then 

 everted over the tip of the forefinger of the other hand, or over a probe 

 laid flat against the middle of the lid. Where the interior of the eye 

 must be examined it is useless to make the attempt in the open sun- 

 shine or under a clear sky. The worst cases, it is true, can be seen 

 under such circumstances, but for the slighter forms the horse should 

 be taken indoors, where all light from above will be shut off, and 

 should be placed so that the light shall fall on the eye from the front 

 and side. Then the observer, placing himself in front of the animal, 

 will receive the reflected rays from the cornea, the front of the lens 

 and the back, and can much more easily detect any cloudiness, opac- 

 ity or lack of transparency. The examination can be made much 

 more satisfactory by placing the horse in a dark chamber and illu- 

 minating the eye by a lamp placed forward and outward from the 

 eye which is to be examined. Any cloudiness is thus easily detected, 

 and any doubt may be resolved by moving the lamp so that the 

 image of the flame may be passed in succession over the whole sur- 

 face of the transparent cornea and of the crystalline lens. Three im- 

 ages of the flame will be seen, the larger one upright, reflected from 

 the anterior surface of the eye ; a smaller one upright, reflected from 

 the anterior surface of the lens ; and a second small one inverted from 

 the back surface of the lens. 



So long as these images are reflected from healthy surfaces they 

 will be clear and perfect in outline, but as soon as one strikes on an 

 area of opacity it will become diffused, cloudy, and indefinite. Thus, 

 if the large upright image becomes hazy and imperfect over a partic- 

 ular spot of the cornea, that will be found to be the seat of disease 

 and opacity. Should the large image remain clear, but the small 



