MICROBES, OR BACTERIA. 



129 



presents the same transition from green to red (Fig. 

 66). Green-tinted snow may be found adjacent to 

 the red snow, and under the microscope it displays 

 minute green globules, identical, except in colour, with 

 those of the red-tinted snow. 



The variety of colour in these microbes is extreme. 

 Micrococcus aurantiacus gives an orange colour to 



Fig. 67. Bacterium cyanogenum, microbe of blue milk (Neelsen). It is probable 

 that several different forms are here contused under this name. B, zoogloea. 



bread and eggs; M. chlorinus is grass-green ; M. cyanus 

 is of a beautiful azure blue ; M. violaceus is violet or 

 lilac, and M. fulvus is rust-coloured. These have all 

 been observed on food. M. candidus forms little 

 white patches upon cheese. 



The genus Bacterium also furnishes its contingent 

 of coloured species ; such are B. xanthinum and 

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