110 



HEALTH AND DISEASE 



transparent cornea forming the front of the eye. Looking through the 

 cornea he will observe the curtain behind it which gives the colour to 

 the eye, and is therefore termed the iris, with the opening in the centre 

 of it, the pupil, through which the light passes, carrying with it the image 

 which is to be depicted on the retina. At the edge of the pupilary opening 

 the small black, pea-like bodies, which have been described as the corpora 

 nigra, will be seen ; small, or even extremely minute, at the lower edge of 

 the pupil, considerably larger at the upper edge, these little bodies are 



worth particular attention, because 

 they are constantly taken by the 

 inexperienced for a diseased con- 

 dition of the eye. Looking through 



a 



Fig. 247. Examination of the Eye (a, the Haw) 



Fig. 248. Fundiis of the Eye 



1, Entrance of the Optic Nerve to form the 

 Retina. 2, 2, Blood-vessels entering around 

 it (there is no arteria cen trails retinse in 

 the horse as in man). 3, Divided Sclerotic. 

 4, Divided Choroid. 5, Divided Retina. 



the pupilary opening, if the eye is in the proper position, the examiner 

 will see a small pearl-like body at the bottom of the posterior chamber 

 which marks the entrance of the optic nerve (fig. 248, l); this body is 

 worthy of particular notice as it is frequently mistaken for a cataract. 



A quarter of an hour occupied in this examination every day for a week 

 should make the tyro familiar with some of the more important parts of the 

 anatomy of the visual organ and its appendages, so that he will be able to 

 recognize any decided changes resulting from disease without running the 

 risk of making the curious mistakes which are so extremely common. 



During the examination the observer will note that the eye of the horse 

 is never for more than a second in one position. In examining the eye of a 

 friend this difficulty entirely vanishes, as the organ can be kept perfectly 

 still while the inspection is being made, but there are positively no means 



