164 GEKLACH ON THE ITCH AND MANGE. 



eruption ; but referring to the spread of the disease, it is of 

 course evident that a male acarus or unimpregnated female 

 can only induce a temporary eruption on healthy skin. The 

 contagion is usually immediate, and generally from persons 

 sleeping with each other, inasmuch as acari do not adhere to 

 clothes, and pass from the skin, which is their natural rest- 

 ing place. Moreover, they are most active under the in- 

 fluence of warmth, and according to some authorities they 

 are nocturnal. The sarcoptes of man does not. live, as 

 proved by Bourguignon, on the dog, cat, rabbit, porpoise, 

 r:at, or birds. On three different occasions Gerlach placed 

 three, four, and five pregnant female acari on those portions 

 of horses' skins which were finest and least covered with 

 hair. Irritation supervened, and even papulae formed. In 

 one case recovery was not complete until the 18th day. 

 Nothing was perceived after placing acari on oxen, sheep, 

 and pigs. In cats and dogs temporary disturbance resulted. 

 One dog recovered only after eight weeks. 



An inveterate form of human scabies was first observed 

 by Bock in Norway, and hence received the name of Scabies 

 Norwegica Boeckii, or Scabies Crustosa. It was believed to 

 be a specific form confined to Norway, but was afterwards 

 observed by Fuchs in Gottingen, Hebra in Vienna, Gumpert 

 in Wiirzburg, and Eigler in Constantinople. The disease is 

 chronic, and attended with the development in different parts 

 of the body of scabs, half-an-inch in thickness, and consist- 

 ing of epithelial scales, dried exudative matter, the spawn 

 and excrement of acari. Beneath these scabs living acari 

 are observed. Fuchs, Hebra, and Gerlach are in favour of 

 the view that this form of itch is similar to the common 

 variety, only aggravated, perhaps, from constitutional taint 

 Gerlach adds the reasons which seem to warrant the con- 

 clusion he has arrived at. 



