404 CHOLERA. 



closely resembles Koch's spirillum in microscopic appear- 

 ances, though it is rather thinner and smaller. Its growth 

 in gelatine is also somewhat similar, but liquefaction pro- 

 ceeds more rapidly, and the bell-shaped depression on the 

 surface is larger and shallower, whilst the growth has a 

 more distinctly yellowish tint. The colonies in plates also 

 show points of resemblance, though the youngest colonies 

 are rather smoother and more regular on the surface, and 

 liquefaction occurs more rapidly than in the case of the 

 cholera organism. The colonies have, on naked-eye ex- 

 amination, a distinctly yellowish colour. The organism does 

 not give the cholera-red reaction, and on potato it forms a 

 thin yellowish layer when incubated above 30 C. When 

 tested by intraperitoneal injection and by other methods it 

 is found to possess very feeble, or almost no, pathogenic 

 properties. Koch found that this organism, when admini- 

 stered through the stomach in the same way as the 

 cholera organism, produced a fatal result in three cases 

 out of fifteen. Deneke's spirillum is usually regarded as a 

 comparatively harmless saprophyte. 



