MICROBES, OR BACTERIA. 131 
The pus of wounds is often coloured blue by 
an aérobic micrococcus, of which the protoplasm is 
colourless, but which makes a colouring matter 
called pyocyanine, and this. gives a blue tint to the 
lint and bandages used for dressing the wound. 
XV. THE MicroBE OF BALDNESS. 
In addition to the numerous parasitic fungi of 
skin on which the hair grows thickly, which we 
have already noticed, the human hair is attacked 
by a true microbe, which is, according to the re- 
searches of Gruby, Malassez and Thin, the cause of 
Alopecia areata, one form of baldness. The parasite 
has the appearance of a micrococcus, and penetrates 
the interior of the hair, which is, as we know, hollow. 
The hair must be made transparent by potash, in order 
to see the microbe. It probably penetrates between 
the bulb and the hair-follicle as far as the root, is 
introduced into the hair, and multiplies and gradually 
rises higher in it, until the substance is disorganized. 
This microbe has been called Bacteitum decalvans. 
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