TYPHOID FEVER. 345 



was destroyed by exposure to the vapour of formalin, while Bacillus 

 coli eommunis and similar bacilli isolated from water gave subcul- 

 tures after exposure for two hours. Typhoid bacilli do not give the 

 reaction for indol, and there is no development of gas in cultures in 

 the depth of nutrient agar containing 2 per cent, of grape-sugar. 

 According to Miiller, sterilised milk is coagulated in twenty-four 

 hours, at 37 C., by Bacillus coli eommunis, but not by the Bacillus 

 typhosus until several weeks have elapsed ; and, further, cultures on 

 acid potato give different results. The typhoid bacillus on micro- 

 scopical examination shows marked polar staining, but Bacillus 

 coli eommunis only shows a slight tendency of the protoplasm to 

 break up. 





FIG. 135. TYPHOID BACILLI IN A SECTION OF SPLEEN, x 800 (FLUGGE). 



Kitasato suggested the negative indol test, and recommended 

 Salkowski's method. Broth-cultivations are treated with a solution of 

 sodium or potassium nitrite : 1 cc. of the nitrite solution (-02 gr. to 

 100 cc. of water) is added to 10 cc. of a broth-culture after twenty- 

 four hours in the incubator, and on adding a few drops of strong 

 sulphuric acid, the typhoid cultures remain colourless, but cultures 

 of bacilli apparently identical give the red colour. On the other 

 hand, Losener maintains that he has cultivated from earth, water 

 and healthy human evacuations bacilli which could not be distin- 

 guished from typhoid bacilli by any of these tests. 



The detection of the typhoid bacillus in water has been 



