PERSONAL APPEARANCES IN HEALTH AND DISEASE. 77 



people it is less abundant, and in the curious type of 

 "albinoes" there is no pigment at all in the choroid. 

 As this choroidal pigment subserves a definite use in 

 vision, causing the absorption of extraneous rays, such 

 people are unable to see in strong direct light, and 

 consequently in the bright light, or even in the simple 

 diffused light of day, they are obliged to keep their eyes 

 half closed in order to see anything. 



The glassy cornea sometimes becomes opaque, or the 

 seat of opaque white patches from inflammation. The 

 glazing of the eye in death is produced by the shrinking 

 of this same structure. Another change affecting the 

 cornea, as old age approaches, is the formation of an 

 opaque white line around the margin of the cornea, and 

 travelling round it, so that it does not at first make a 

 complete circle ; it is known as the arcus senilis. It is 

 part and parcel of the degeneration of tissues which is the 

 natural accompaniment of age. Another old-age condi- 

 tion, which sometimes takes place, is the hardening and 

 opacity of the crystalline lens known as cataract, such 

 opacity being visible to the observer through the pupil. 



Having just mentioned the case of " albinoes " it' may 

 be convenient to sum up their characters now and have 

 done with them. A true " albino" is one whose skin, 

 hair and eyes are wholly devoid of pigment from birth 

 onwards. The skin is thin and fair, the delicate flesh- 



