38 LESSONS IX HORSE JUDGING. 



foremost half of the capsule of the lens (our fore- 

 most watch-glass) is bent like a bow that is having 

 its string pulled in the act of shooting, and the 

 lens is thus altered in its convexity from being 

 shaped like B to being shaped like C, Fig. 5. 



The lens of the eye is quite clear and transparent 

 like glass, when in health ; but from accident, 

 disease, or old age, it may become opaque and 

 milky, and then the eye is said to have a ' cataract.' 

 ' Cataract' may occur from a horse falling on his 

 head whilst hunting, or in rearing and falling back 

 and knocking the head violently against the ground ; 

 or by knocking the head violently against the top 

 of a doorway — any violent blow on the head, in 

 fact. It does so by rupturing the capsule of the 

 lens (one of our watch-glasses) and letting in the 

 ' watery humour' which occupies the front chamber 

 of the ej'e, and which is marked x x x x in our 

 diagram (Fig. 5, D). When the ' watery humour' 

 gets into the substance of the ' lens' through a rent 

 in the capsule, the ' lens' immediately begins to 

 swell and become milky and opaque, and in a da}^ or 

 two the whole lens is swollen and white like milk. 

 Disease causes ' cataract,' notably that disease in 

 which a patient passes quantities of sugar with his 

 water. Old age produces ' cataract,' by the lens 

 shrinking and altering its proper structure. 



AVhen the ' cataract' is complete, that is to say, 

 when the whole lens is affected, you see the milky 

 white lens through the pupil, or in other words. 



