Page:Popular Science Monthly Volume 14.djvu/527

Rh strong, short legs, terminating in long spines (Figs. 10 and 11). The feet and nippers are provided with suckers. They have no eyes; but, with their habits of life, the absence of these organs causes them no inconvenience. The impregnated female digs a long burrow in the skin, depositing her eggs as she moves. If one of the early vesicles of the itch is examined, a small spot may be seen upon some point of the surface; this is the opening made by the mite to begin its tunnel; leading from this, a white, fluted line may be traced, which is the cuniculus or burrow of the acarus, and the fluted or dotted appearance is due to the eggs, the white dots showing where they lie (Fig. 12).

The burrow varies in length, sometimes reaching half an inch, and at its end, under a slight elevation, lies the mite. The cut shows a burrow with a number of empty shells scattered along the line, with one unhatched egg close to the mite. Close inspection will reveal a small, dark point at the end of the burrow; and, if the skin be raised there with the point of a needle, the creature can be brought to view and easily extracted. The itch-mite is never found in a vesicle or pustule; indeed, there is no connection between the later vesicles and the burrow; they are evidently caused by the proximity of the mite. The larvae and young females hide themselves in broken surfaces, or burrow a short distance into the skin; the male retreats under any protecting edge. The advance of civilization, with its increased use of soap and water, has done much toward exterminating this pest; the "Jackson itch" and "seven-year itch" are much less heard of than formerly; but wherever, as in army life, men are crowded together, and personal cleanliness is neglected, it reappears in a most flourishing condition. The disease must, of course, be conveyed by transference of the mite from those who are infected to those who are sound;