ISOLATING THE TYPHOID BACILLUS. 431 



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'S METHOD. Hunter 1 recommends the use 

 of neutral red as a differential test. He employs it in 

 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 detection 

 of bacillus typhosus in water. In this method they tried to 

 bring about a separation of bacillus typhosus and bacil- 

 lus coli on the basis of their fermenting properties in 

 such a manner as not to hinder the growth of bacillus 

 typhosus, but rather to make the conditions of growth as 

 favorable 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. 

 These substances were added to sterile litmus agar in 



i Hunter : The Lancet, March 2, 1901. 



2v. Drigalski and Conradi: Zeitschrif fur Hygiene, Bd. 89, 1902 

 p. 283. 



