Micrococcus. 9 



sap-green mucous masses, or in fluids sap-green layers, 



which by degrees colour the whole fluid yellow-green. 



On boiled eggs. 



The colouring matter is soluble in. water; it is not reddened by- 

 acids. 



6. M. cyaneus, Cohn (J.c, p. 156). 



Bacteridium cyaneum, Schroter. 



Cells elliptic ; producing on slices of potato an intense 

 blue, which penetrates also into the interior, or even to the 

 opposite side of the slice. In fluids it forms a zooglcea, 

 which at first is colourless, then bluish-green, and at last 

 intense blue. 



On boiled potatoes. 



The colouring matter is soluble in water ; the solution is at first 

 verdigris-green, but afterwards usually becomes clear blue. It is 

 coloured intense carmine by acids, and then by alkalies blue or sap-green 

 respectively. In the spectroscope it shows no absorption bands, but 

 only a darkening of the less refractive half. 



7. M. violaceus, Cohn {I.e., p. 157). 



Bacteridium violaceum, Schroter. 



Cells elliptic, larger than those of M. prodigiosus ; 

 occurring in bright violet-coloured gelatinous drops, which 

 unite to form larger spots, reaching 6 mm. in diameter. 



On boiled potatoes. 



B. — Zymogenous Species. 



8. M. ureae, Cohn {I.e., p. 158). 



Cells round or oval, i"2S-2 /tin diameter; isolated or 

 concatenate or forming a zooglcea on the surface of the 

 fluid. (Fig. 4^.) 



In urine. 



M. urece is the ferment of ammonia fermentation. If fresh urine is 

 allowed to stand exposed at a sufficient temperature (30° C), it loses its 



