MICROBES, OR BACTERIA. 131 



The pus of wounds is often coloured blue by 

 an aerobic micrococcus, of which the protoplasm is 

 colourless, but which makes a colouring matter 

 called pyocyanine, and this gives a blue tint to the 

 \int 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 Th,in, 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 Bacterium decalvans. 



