common assertion that living forms are a matter of course in everything that we eat and drink is without warrant. While it is true that water and one or two other articles usually contain microscopic organisms, the idea commonly conveyed by such statements is erroneous. These degraded and disgusting forms are not proper food-stuff; nor is their consumption unavoidable. Pure articles, in an undamaged condition, do not contain them; and their presence in numbers in any article of food is proof that it is unfit for human use, and should be rejected.
There are several species, placed by later authors in the same genus with the sugar-mites, whose normal habitat seems to be on food, insect collections, and in the dust and mold of cellars and damp places, but which, when transferred to animal bodies, become parasitic, causing curious and painful disorders. Signor Moriggia figures a singular horny excrescence which grew from the hand of a lady. It was nearly eight inches long, tapering upward from a wide base, 
Fig. 8.—Cheyletus eruditus. and curved toward the wrist. Its cavities were swarming with a species of acari. Another species was found by Hering in the hind feet of a horse, that, although young and in other respects sound, had to be killed. The hoofs were quite disorganized, the frog and sole consisting of a soft, fibrous mass, secreting an offensive liquid; in the end, the sore spread to the flexors and muscles of the fetlock. A negro inmate of the Seaman's Hospital, London, suffered from large and peculiar sores on the soles of the feet. Examination by Prof. Busk revealed the presence of a mite, which was doubtless the cause of the trouble. The negro attributed the disease to wearing a pair of shoes which were lent for a few days to another negro who was similarly afflicted. The latter came from Sierra Leone, and inquiry proved the existence of a pustular disease, native to that place, called craw-craw, a species of itch very troublesome to cure.
The genus Cheyletus is a very remarkable type. It is unquestionably carnivorous, its palpi being adapted for holding its prey. They are not gregarious in their habits; but, like all animals that live by rapine, are solitary. When placed in company with the cheese-mites, they seize them between their palpi, and, plunging their beaks into the body, suck up the juices. The C. eruditus (Fig. 8) appears also
