456 APPLIED BACTERIOLOGY 



and polluted water. It forms short rods, with rounded 

 ends. Grows at the ordinary temperatures. It is patho- 

 genic to mice and guinea-pigs, the bacilli being found in 

 the blood and organs. Cultural characters : 



Gelatine Plates. — On the surface the colonies form at 

 first nail-like, slimy growths, which are of a dirty-white 

 colour ; later they lose this slimy character, and form large 

 circular grayish centres, with concentric rings. The 

 gelatine is not liquefied. 



Gelatine Tubes. — Forms a moist, shining, yellowish-brown 

 expansion, which later becomes thick and spreads over the 

 whole surface. 



Potatoes. — A yellowish expansion forms, which rapidly 

 spreads over the whole surface. 



Spirillum Tyrogenum (Deneke's Cheese bacillus). — This 

 organism was found by Deneke in 1885 in old cheese. In 

 microscopical appearance it resembles the cholera spirillum, 

 from which it is distinguished by the absence of indol, 

 when tested by the indol reaction. The organism is a 

 little smaller than the cholera spirillum. It forms long 

 spiral threads, which are exceedingly motile. Cultural 

 characters : 



Gelatine Plates. — The colonies are similar to those 

 formed by the cholera spirillum and by the Finkler-Prior 

 bacillus, except that they are brownish in colour. 



Gelatine Tubes. — Grows very rapidly, as in the plate- 

 cultivation, giving rise to liquefaction of the gelatine, not 

 so rapidly as the bacillus of Finkler and Prior, but more 

 rapidly than the cholera spirillum. 



Agar-Agar. — Forms a dirty yellowish-white expansion. 



Potatoes. — A yellow expansion is formed. 



Bacillus Violaceus {B. Jacinthus). — This organism has 

 been found by various investigators in water. It occurs in 



