486 DISEASES OF THE SKIN 



and caused by more than twenty species of the fungi : Aspergillus, 

 Penicillium, Monilia and Montoyella. 



It is contagious, but Europeans are rarely attacked. 



The Aztecs of Peru prayed about it centuries before the Spanish 

 conquest. 



SYMPTOMS. 



There is desquamation and itching of the patches, the first of which 

 may be red, white, blue or black, the varying tints being due perhaps 

 to the variety of the fungus. 



When the scalp is affected the hair turns grey, becomes thin and 

 falls out. One person may show different tints, but the patches them- 

 selves do not change in colour. 



The superficial type is usually blue or black and spreads rapidly. 

 The deep type is usually red or white and spreads slowly, and is more 

 difficult to cure. 



TREATMENT. 



Destroy all old clothes. Absolute cleanliness. 



Apply chrysophanic acid, sulphur, resorcin, liniment of iodine or 

 other epiphyticides. 



PITYRIASIS. 

 P. versicolor. 

 See Tinea versicolor. 

 P. rubra. 

 See Dermatitis exfoliativa. 



PRICKLY HEAT. 



A papular or papulo-vesicular eruption with marked pruritus con- 

 nected with profuse sweating so common in all hot climates. 



Anything resulting in perspiration in hot climates may cause it. 



The theories of its causation are as follows : — 



(i) Sodden cells of sweat glands swell and obstruct the orifice of 

 the sweat duct (Pollitzer). 



(2) Acute distension of sebaceous glands by their own secretion 

 (Pearse). 



(3) An infective disease caused by a very minute but active amoeba 

 (Durham). 



Numbers (i) and (2) may both be present, and infection is not at 

 all improbable through scratching. 



The disorder is not serious in robust people, but to weaklings it 

 may be serious from loss of sleep, &c. 



TREATMENT. 



Avoid all causes of excessive perspiration. 

 Avoid copious drinks and all alcoholics. 



