OF THB HUMAN SKIN. 83 



applied to it. It is sufficient to state here that 

 chloasma, liver spots, and the yellowish or brown- 

 ish discoloration of the skin, are entirely due to 

 irregularly distributed or increased amount of the " 

 pigment of the skin, which, according as it is pres- 

 ent in greater or less quantity, causes the differ- 

 ence of color in the various races of mankind. 

 The parasitic affection we are speaking of, also 

 renders the surface of the skin of a more or less 

 dark brown color; hence the laity, and, we must 

 add, only too many physicians, confound them. 

 The technical name of the affection is pityriasis 

 versicolor, although it has nottiing to do with ordi- 

 nary pityriasis, the name having been given to it 

 from its varying color, and long before its cause 

 was discovered by Dr. Eichstadt in 1846* This 

 cause is the presence in the scarf-skin of a fungus 

 called Wiicro^oronjurjur, a vegetable growth con- 

 sisting of oval or rounded spores, of considerable 

 size, and usually collected into large clusters like 

 bunches of grapes. Besides these we have under 

 the microscope the jointed and branching tubes. 

 The spores and tubes are also found on and in the 

 hairs, but not to such an extent as in ringworm of 

 the head or body. 



