MITES, TICKS, AND OTHER A CAR I 



511 



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). 



Fig. 10.— Two of the Posterior Legs of 

 the Male Sarcoptes scabiei. 



Fig. 11.— Two of the Posterior Legs of 

 the Female Sarcoptes scabiei. 



The burrow varies in length, sometimes reaching half an inch, and at 

 its end, imder a slight elevation, lies the mite. The cut shows a bur- 

 row 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 bur- 

 row ; 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 togetlier, and per- 

 sonal cleanliness is neglected, it reappears in a most flourishing con- 

 dition. The disease must, of course, be conveyed by transference 

 of the mite from those who are infected to those who are sound ; 



