VARIATIONS IN TYPHOID BACILLI 281 



of five months and then plated on neutral red dulcitol agar yielded only- 

 fermenting colonies. Twenty colonies from a MacConkey plate of pure 

 typhoid were inoculated into dulcitol broth; the time required for acidity 

 to appear varied from eleven to thirty-two days. Slow fermenters of 

 dulcitol died in dulcitol broth in two months while quick fermenters 

 remained alive longer. He found one strain which did not ferment ara- 

 binose, but which after three months' subculturings became a quick 

 fermenter. Three strains that did not ferment glycerol became after 

 eight months' subcultivation quick fermenters, but never in less time 

 than three to four days. In plating out on glycerol media he found a 

 mixture of quick and slow fermenters. 



Reiner Mliller (1908, 1911) did not observe acid production in rham- 

 nose by any of his typhoid cultures and noticed that the colonies on the 

 rhamnose plates remained small and delicate but that 5 per cent rham- 

 nose produced no more inhibition than 0.5 per cent. He showed, 

 further, that other bacteria of the typhoid-colon group are not inhib- 

 ited by rhamnose. He observed no production of acidity by typhoid 

 bacilli on litmus agar containing arabinose, dulcitol or rafiinose, but he 

 observed acidity on rhamnose Endo agar. 



Bull and Pritchett (1916) found an atypical typhoid strain 

 showing irregularity in fermentation, glucose, levulose, and 

 dextrin being all positive and the other sugars negative; indol 

 being positive as in the case of Bad. coli, but the organism 

 agglutinated m 1:20,000 dilution. 



Krumwiede, Kohn and Valentine (1918) inoculated thirty- 

 seven strains of Bad. typhosum into xylose broth and found that 

 twenty-nine produced acid in twenty-four hours while eight of 

 the strains required from five to thirteen days for this result. 



Winslow, Kligler, and Rothberg (1919) recently reported the 

 results of similar investigations of various bacteria. They 

 describe the typical typhoid bacillus as a Gram-negative, non- 

 spore-forming rod, actively motile. It forms translucent irregular 

 colonies on gelatin media and faint, nearly colorless growths on 

 potato. It produces strong and prompt acid but no gas in media 

 containing the hexoses, maltose, mannitol, sorbitol, xylose and 

 dextrin; it does not attack arabinose, rhamnose, or lactose; 

 produces a sHght initial reddening of litmus mUk, which after 

 two weeks reverts to a neutral or slightly alkaline reaction. It 



