ISOLATING THE TYPHOID BACILLUS. 445 



It is interesting to note that in this test the usual 

 reactions produced by these organisms in peptone media 

 containing the ordinary fermentable carbohydrates, such 

 as glucose and lactose, are reversed. 



The authors state that this method has thus far shown 

 itself to be infallible for the differentiation of cultures 

 of typhoid and colon bacilli obtained by them from 

 every available source. 



Hunter 1 recommends the use of neutral red as a dif- 

 ferential test. He employs it iii the proportion of 0.5 

 to 1.0 c.c. of a saturated watery solution to 10 c.c. of 

 nutrient agar-agar. The reducing action of the colon 

 bacillus causes the color to become yellow, while the 

 normal red color is not affected by the typhoid bacillus. 



METHOD OF v. DRIGALSKI AND CONRADI. v. Dri- 

 galski and Conradi 2 published a method for the detec- 

 tion of bacillus typhosus in water. In this method 

 they sought to bring about a separation of bacillus 

 typhosus and bacillus coli on the basis of their ferment- 

 ing properties. This they sought to do in such a man- 

 ner as not to hinder the growth of bacillus typhosus, 

 but rather to make the conditions of growth as favor- 

 able as possible. Their studies of the fermentative 

 properties of bacillus typhosus and bacillus coli were 

 carried out upon the following carbohydrates : 



1. Monosaccharides : Of hexoses : glucose, fructose, 

 galactose, mannite and dulcit. Of pentoses : arabinose, 

 xylose, and rhamnose. 



2. Disaccharides : Saccharose, maltose, lactose. 



3. Polysaccharides : Amylum, inulin, and dextrin. 



1 Hunter: The Lancet, March 2, 1901. 



2 v. Drigalski and Conradi : Zeitschrift fur Hygiene, Bd. 39, 1902, 

 t 283. 



