PLATE XXI. 

 Bacillus cyanogenus. 



Bacterium syncyanum. 

 Bacillus of blue milk. 



FIGS, i and 2. 



Potato inoculated from a cultivation in nutrient gelatine. 

 In three days a peculiar bluish-green growth 

 develops on the surface of the potato, and in 

 nine days it has a heaped-up margin of a bluish- 

 green colour, while the central portion has turned 

 almost black. 



