Cultivation 49 1 



of sulphuric acid, so that 10 c.c. have an acidity neutralized 

 by 0.2 c.c. of one-half normal soda solution. This acidity 

 is equal to 0.5 c.c. sulphuric acid per liter. After shaking, 

 place the flask in a steam sterilizer for ten minutes, then 

 filter. When filtered, verify the acidity of the medium, 

 correcting if necessary. Finally, add the magnesium sul- 

 phate, dissolve, dispense in tubes, and sterilize by the inter- 

 mittent method. 



At the moment of using, put into each tube i c.c. of a 

 35 per cent, solution of lactose and o.i c.c. of a 2.5 per cent, 

 solution of carbolic acid. 



Upon this medium, the colonies of the typhoid and colon 

 bacilli show marked differences. The colon colonies are 

 yellowish -brown, the typhoid colonies bluish-white and 

 small. Fine bubbles of gas from the fermentation of the 

 lactose often occur about the colon colonies. 



By this method Remy was able to isolate the typhoid 

 bacillus from the stools in 23 cases which he studied. He 

 believes that the constant presence of the typhoid bacillus 

 in the stools of typhoid fever, and its absence from them 

 under all other conditions, is a far more important and 

 valuable method of diagnosis than even the Widal reaction. 



Kashida * makes the differential diagnosis by observing 

 the acid-production of Bacillus coli in a medium consisting 

 of bouillon containing 1.5 per cent, of agar, 2 per cent, of 

 milk-sugar, i per cent, of urea, and 30 per cent, of tincture 

 of litmus. This is the so-called litmus -lactose- agar -agar. 

 The culture medium should be blue. When liquefied, 

 inoculated with the colon bacillus, poured into Petri dishes, 

 and stood for from sixteen to eighteen hours in the incubator, 

 the blue color passes off and the culture medium becomes 

 red. If a glass rod dipped in hydrochloric acid be held 

 over the dish, vapor of ammonium chlorid is given off. The 

 typhoid bacillus produces no acid in this medium, and there 

 is consequently no change in its color. Upon plates with 

 colonies of both bacilli, the typhoid colonies produce no 

 change of color, while the colon colonies at once redden the 

 surrounding medium. 



Rothberger t first employed neutral red for the differentia- 

 tion of the typhoid and colon bacilli. When grown in fluid 

 media containing it, the colon bacillus produces a yellowish 



*"Centralbl. f. Bakt. u. Parasitenk.," Bd. xxi, Nos. 20 and 21, 

 June 24, 1897. 



f'Centralbl. f. Bakt.," 1893, p. 187. 



