18 ANIMAL PAKASITES. 



dead bodies, the contents of one or several vesicles may be pressed 

 out by placing the nails npon the skin about 2 3 lines apart, 

 and then moving them towards each other. By this manoeuvre 

 the contents of the glands often issue in long rolls. Others use 

 hard instruments for this purpose* such as the handles of lancets ; 

 Simon employed a hair pin, or a thin bent sound. 1 With this 

 pressure is to be applied in the neighbourhood of the vesicle. I 

 prefer the former process, because the person to be examined may 

 perfectly well apply the pressure with his own nails, and the sur- 

 geon keeps his hands free for the collection of the masses pressed 

 out. We usually find an Acarus when we spread these masses 

 upon a glass, facilitate their diffusion by a gentle pressure, and 

 add a drop of (red) Macassar oil. Frequently, however, the 

 result is negative, especially with enormously developed vesicles, 

 and I have sometimes only attained my object by again pressing 

 the spot which has been pressed once already. In the sebaceous 

 matter which then issued, and which was collected with a knife, 

 I found the animals very easily. In dead subjects I have also 

 evacuated them by pressure, but here the animal often retires 

 very deep, and nearly to the origin of the follicle. In such cases 

 we can frequently only obtain the animal by cutting through the 

 skin. In the nose and other parts which cover, open cavities in 

 corpses, we may, in case of need, introduce a broad, firm instru- 

 ment, such as a spatula, into the cavity, and press a glass plate 

 against it from without, so as to collect the sebaceous matter at 

 once upon the glass. The collection of the animals is most easily 

 effected in fat people. But this probably varies according to the 

 general faculty of the skin, to give up the contents of the cuta- 

 neous follicles with greater or less ease on pressure. If there is 

 difficulty, the outer covering of the pustules may be first of all 

 pricked, or removed by the knife. We shall then find that the 

 animals occur in extreme abundance, and that authors like Wilson, 

 according to whom but few men are free from the mites, are in 

 the right. 



Mode of life of the mites. They occur sometimes singly, some- 

 times several, sometimes many (13) together in one hair-follicle. 

 In hair-follicles into which small sebaceous glands open, the 

 animals lie close to the hair; in the large composite sebaceous 

 glands, into which small hair-follicles open, they take up their 



1 Hebra makes use of a rather wide watch-key, the opening of which he places on 

 the most prominent spot and then presses. 



