ITCH MITES, 295 



CASE maturity, and it is a few days after one of these changes that it 

 obtains its additional posterior pair of legs. This pest was 

 formerly much commoner than it is now. Soap and water, or 

 their synonym cleanlier habits, have rendered it comparatively 

 scarce, but whenever numerous bodies of men are crowded 

 together without time and opportunity to attend to their personal 

 cleanliness, then it reappears and spreads like wild-fire. All 

 armies are great sufferers from this and louse vermin. The 

 Americans found it so prevalent during their wars, that the 

 common people supposed it was something special and peculiar. 

 " The army itch," " the seven years' itch," " the Jackson itch," 

 are all only the common itch developed by the special circum 

 stances of the case into a peculiarly flourishing condition. 



Our great English authority on skin diseases. Dr. Erasmus 

 Wilson, gives the following as the indications of an attack by 

 this insect, viz., firstly, a peculiar scaliness and undermined state 

 of the epidermis, which is not met with in other cutaneous 

 affections \ secondly, the presence of conical vesicles, with 

 acuminated and transparent points; and thirdly, and principally, 

 the presence of the mite itself, which may be extracted from its 

 retreat beneath the loosened epidermis with the point of any 

 sharp instrument. The diseases which he mentions as apt to be 

 confounded with it, are eczema, prurigo, lichen, impetigo, and 

 ecthyma. 



AVhen one of the early vesicles of the itch is examined with 

 attention, a minute spot or streak may be observed upon some 

 one point of its surface. This is the aperture originally made 

 by the insect on its first entrance within the epidermis, and 

 from this spot or streak a whitish fluted line may be traced, 

 either in a straight or a curved direction into the neighbouring 

 epidermis. 



The whitish line is the cuniculus, or burrow of the acarus ; and 

 the fluted or dotted appearance is due to the eggs, the white dots 

 indicating the points where the eggs lie. The burrow necessarily 



