THE SKIN. 359 



be rubbed with oil of turpentine or some oatmeal, as a 

 precaution against any increase of the parasites ; though 

 this is hardly necessary^ it is as well not to reject the 

 precaution. Acariasis is not frequent in the ox, but is 

 most prevalent in badly kept dirty herds, and is generally 

 associated with debility, which is traceable to the irritation 

 by the parasite being a constant source of worry. The 

 Acarus is the sole cause, and we cannot generate it by 

 any combination of ordinary causes. Nevertheless, it may 

 be that the skin of the weak animal forms a more con- 

 genial nidus for the acarus than that of an animal in 

 good health, and thus weakness becomes a predisposing 

 cause. 



In the treatment of mange our efforts must be directed 

 to the destruction of the parasites. Also, it is necessary to 

 remember that after this has been accomplished the ova may 

 remain intact and undergo development in due course. 

 Two conditions lead to obstinacy of this disease (not so 

 marked in the ox as in some other animals) — the concealed 

 state of the parasites and the powers of resistance of the 

 ova. We must break down and remove the scales, and 

 generally must repeat our dressings at intervals, to de- 

 stroy the young Acari as they appear from the ova. The 

 removal of the epidermic debris may be best accomplished 

 by friction with a weak alkaline solution, as ordinary soft 

 soap and water. Subsequently, the solution of liver of 

 sulphur, tar, and turpentine liniment, arsenical wash, 

 solution of bichloride of mercury, or other anti-parasitics, 

 may be applied with care ; stavesacre or tobacco infusion 

 are also used for this purpose, and many prefer sulphur 

 ointment, or even simple reagents, which prevent access of 

 air to the Acari and thus suffocate them. When making 

 use of poisonous applications we must remember that 

 they are liable to become absorbed or to be ingested, 

 from animals licking themselves or one another. Another 

 practical inference is to frequently change the dressing in 

 any particular case, for the Acari seem to become tolerant 

 of some of the agents, which do not cause their death, 

 but simply their departure. The desirability of adop- 



