692 DISEASES OF THE SKIX. 



scales on the arm, and burrow into tlie skin at tlie part covered 

 by the scab. On removing the latter, the parasite is seen as a 

 white spot on a somewhat reddened skin, or upon a small red 

 papula. With the point of a needle the white summit of the 

 epidermic vesicle is punctured, and the sarcoptes obtained. If 

 the inflammatory nodule be allowed to pass to the state of a 

 bladder, then the mite is rarely found. If there be only a 

 few acari on the scales applied to the arm, the red points or 

 nodules are only seen next day, and before the appearance of 

 this eruption the insects are not, as a rule, to be found on the 

 skin ; if many of the parasites exist on the scales, then in the 

 course of a few hours they may be obtained on the arm. 



" The dermatodectes, esj)ecially of horses and cattle, are 

 readily found in a similar way. Sometimes the scales need 

 only be on the human skin one hour. 



" When sarcoptes are sought by placing scabs on the skin of 

 the arm, lest any should remain bare behind, the skin should 

 be rubbed with a little oil of turpentine or some oatmeal. With 

 the other forms of parasites mentioned this precaution is un- 

 necessary." 



Syiii'ptoms of Mange in the Horse. — As already indicated, there 

 are three varieties of mange, each being due to a particular 

 parasite, which seems to induce symptoms differing in some 

 particulars. The first variety (sarcoptes) causes a vesicular erup- 

 tion and intense itching, which increases towards night. This 

 pruritis is supposed to be due to an acrid fluid or saliva which the 

 parasite deposits in the gallery in which it is lodged. 



The favourite seats of this form of mange are the sides of the 

 neck and withers, whence they may extend over the surface of 

 the body, except, according to Mr. Fleming, those parts covered 

 by long hair, as the root of the mane and the tail. 



If the invaJed parts be examined by the hand, small hard 

 pimples may be felt, which, if looked at closely, will be found 

 to consist of a small scab easily removed, exposing round 

 small moist surfaces about an eighth of an inch in diameter. 

 The character of this form of scabies is eczematous, and at a 

 more advanced period large surfaces become destitute of hair, 

 and are covered with dry powdery crusts of variable thicknesses. 

 At a later period the skin becomes thickened, wrinkled, and 

 fissured, assuming the appearance of the skin of the rliinoceros. 



