THE BACILLUS OF TYPHOID FEVEK. 367 



mended by Smith for making this test is a peptone-bouillon contain- 

 ing two per cent of grape sugar and made slightly alkaline with 

 carbonate of soda. The liquid becomes clouded throughout at the 

 end of twenty-four hours, but not a trace of gas is developed even 

 after several days. On the other hand, the colon bacillus and other 

 bacilli which closely resemble the typhoid bacillus cause an abundant 

 development of gas in this medium. 



The method of Wurtz will be found useful in the detection of 

 colonies of the typhoid bacillus in plate cultures from contaminated 

 water, etc. This consists in the addition to the nutrient medium of 

 lactose (two per cent) and a solution of litmus. When the colonies 

 develop in plates made from this medium the typhoid colonies re- 

 main blue, while colonies of the " colon bacillus " have a red color, on 

 account of the development of lactic acid. 



Schild (1894) uses a bouillon containing formalin (1:7,000) and 

 claims that the typhoid bacillus fails to grow in this medium, while 

 the bacilli of the colon group multiply in it and cause the me- 

 dium to become clouded within twenty-four hours. Abel (1894), as a 

 result of extended experiments, arrives at the conclusion that the 

 formalin test cannot be relied upon for distinguishing the typhoid 

 bacillus from certain similar bacilli, which also fail to grow in for- 

 malin solution. But, on the other hand, a bacillus which grows in 

 bouillon containing 1 : 7,000 of formalin can be definitely pronounced 

 to be not the typhoid bacillus. 



Eisner (1895) recommends the following method for the detection 

 of the typhoid bacillus in water or in f aaces : To potato gelatin, pre- 

 pared by the method of Holz, he added one per cent of potassium 

 iodide. But few species of bacteria will grow in this medium, but 

 Bacillus coli communis grows in it luxuriantly, forming fully de- 

 veloped colonies at the end of twenty-four hours. The typhoid col- 

 onies, on the contrary, are only just visible under a low power at the 

 end of twenty-four hours, and at the end of forty-eight hours are 

 seen as small, shining, drop-like, very finely granular colonies. At 

 the same time the colonies of the colon bacillus are much larger, 

 coarsely granular, and of a brownish color. By this method Eisner 

 succeeded in obtaining pure cultures of the typhoid bacillus from 

 the faeces in fifteen out of seventeen cases of typhoid fever, in various 

 stages of the disease. Lazarus (1895) has tested this method and re- 

 ports that he succeeded without any difficulty in obtaining pure cul- 

 tures of the typhoid bacillus from the alvine discharges of typhoid 

 patients. 



When the typhoid bacillus and the colon bacillus are planted to- 

 gether, in the same liquid medium, the first-mentioned bacillus, even 

 when in excess at the outset of the experiment, soon disappears and 



