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 awrantiacus gives an orange colour to 
Fig. 67.—Ractertum microbe of blue milk (Neelsen). It is probable 
that several different forms are here confused under this name. B, zoogloea. 
bread and eggs; M. chlorinus is grass-green; M. cyanus 
is of a beautiful azure blue; UM. violaceus is violet or 
lilac, and M. fulvus is rust-coloured. These have all 
been observed on food. Jf. candidus forms little 
white patches upon cheese. 
The genus Bacterium also furnishes its contingent 
of coloured species; such are B. wanthinum and 
7 
