Etiology

Scabies is one of the few diseases of which we can say that we absolutely know the cause; and yet there is no chapter in medical history more interesting than that which concerns the etiology of this affection.

The acarus is exceedingly minute, and when first hatched has but six legs. It soon assumes its adult form, however, with eight legs; and the sexes are easily distinguished by the fact that in the female the four posterior legs are furnished with projecting hairs, while in the male two of these legs terminate in suckers instead of hairs.