THE ORGANS OF SPECIAL SENSE. 237 



himself, and objects to the diseased parts being handled, 

 instead of experiencing pleasure from it, as in the true 

 mange ; in the former disease there is a burning pain of 

 the skin, and the constitution of the patient suffers more 

 severely. The loins, and, in the male, the genital 

 organs, are favourite seats of the disease. Positive dia- 

 gnosis depends on detection of the parasite by microscopical 

 examination ; a few strong hairs persist on the diseased 

 parts when the rest have fallen, and often a demodex may 

 be detected on one of these hairs as extracted by means 

 of the forceps. Again, the mixture of pus and sebaceous 

 matter, as expressed from an inflamed g'and, may be 

 examined under a low power, and in it will be found the 

 acari in various stages of development and their ova ; the 

 sebaceous material may be diluted with a little oil or 

 water to facilitate their detection. Often specimens can- 

 not readily be obtained, then this disease must be distin- 

 guished from non-parasitic eczema by its commencing 

 locally and its gradual extension. The hair-follicle under- 

 goes such disorganisation that bare patches may remain 

 after cure of a bad case ; it is remarkable that the disease 

 conveyed to man from the dog disappears after from a 

 fortnight to a month, whereas that from man to the dog 

 was found by Gruby to spread until the whole body surface 

 was invaded. The earliest indication of this disorder 

 consists in circumscribed loss of hair and the occurrence 

 of red spots, of each of which the opening of a sebaceous 

 gland is the centre, serum forms, and subsequently rather 

 large pustules, which burst, and their contents form scabs. 

 The pustules are often confluent, and the skin of the 

 affected parts is much inflamed throughout. The patient 

 suffers much, and the loss of hair may be so extensive as 

 to render careful clothing of the animal necessary in cold 

 weather. Cracks and other sores form on the surface, 

 and sometimes blood from them mingles with the purulent 

 discharge. Treatment. — The general rules which we have 

 propounded for the treatment of parasitic mange must 

 be remembered and applied here as in "true mange." 

 The local treatment needs to be specially active, because 



