INTESTINAL OR COLON-TYPHOID GROUP 277 



been favorable. It evidently is true that the virulence of the 

 organism is subject to considerable variations, for the careful 

 work of Rosenau showed the culture which he possessed to be 

 worthless in the extermination of rats. On the other hand, there 

 is some evidence that the organism is not so free from harmful 

 effect on the human as has been supposed. Fatal infections in 

 man have been reported from Japan. 



Bacillus pulloram 



Disease Produced. White diarrhea of chicks. 



Rettger and Harvey have described the Bacillus pullorum as 

 the specific cause of a white diarrhea in young chicks. Its etio- 

 logic relation to the disease has been called seriously into question 

 by Morse, Hadley, and others, who believe that it is either a com- 

 mensal or a secondary invader, and that the disease is in reality 

 a coccidiosis. The evidence is somewhat conflicting on this point. 

 The importance of the B. pullorum, even as a secondary invader, 

 renders a description pertinent. 



Morphology and Staining. Bacillus pullorum is a rod, 0.3 to 

 0.5 by 1 to 2.5 ft, with rounded ends. It occurs singly or very 

 rarely in chains. It is non-motile, does not produce capsules or 

 spores. It stains readily and uniformly with ordinary aqueous 

 anilin dyes, and is gram-negative. 



Isolation and Culture. The organism may be isolated from the 

 infected chicks by opening the body with aseptic precautions, 

 and making streaks upon the surface of agar slants with blood 

 or the pulp of the spleen or liver. Upon the agar slant the colonies 

 are discrete, and at first resemble the pin-point, translucent 

 colonies of the Streptococcus. They enlarge later. Upon gelatin 

 the colonies resemble those of the typhoid bacillus. Little growth 

 occurs upon potato. Milk is a suitable medium, but there is 

 little change, no coagulation, and no proteolysis. 



Physiology. The organism is aerobic and facultative anaerobic. 

 The optimum growth temperature is about 37. Dextrose and 

 mannite are fermented, with the production of both acid and gas. 

 Maltose, lactose, and saccharose are not fermented. Indol is 

 not produced. 



Pathogenesis. Experimental Evidence. Rettger has isolated 



