444 BACTERIOLOGY. 



Method of Capaldi and Proskauer. 1 As a result of 

 an elaborate series of experiments, these authors recom- 

 mend the use of two speeial culture-media for the dif- 

 ferentiation of the typhoid and colon bacilli. 



Medium No. 1 consists of: 



Asparagine 0.2 per cent, in distilled water. 



Mannite 0.2 



Sodium chloride 0.02 



Magnesium sulphate .... 0.01 



Calcium chloride 0.02 



Mono-potassium phosphate . 0.2 



Medium No. 2 consists of: 



Witte's peptone 2.0 per cent, in distilled water. 



Mannite 0.1 



Both media are to be sterilized, the reaction brought 

 to the litmus neutral point with caustic potash solu- 

 tion, and enough litmus tincture then added to them to 

 cause a distinct, though not too intense, purple color. 

 After this they are to be again sterilized, when they 

 are ready for use. 



After 20 hours at 37-38 C. typical colon bacilli 

 and the varieties of this organism develop in both solu- 

 tions, but produce add only in medium No. 1. 



The typhoid bacillus grows only in medium No. 2, 

 and its growth is accompanied by the production of 

 an acid reaction. 



The growth of bacillus coli in medium No. 2 is ac- 

 companied by a slight alkaline reaction. 



The alterations in reaction are indicated by the cor- 

 responding changes in the color of the litmus tincture 

 in the media. 



1 Capaldi and Proskauer : Zeitschrift fur Hygiene und Infektious- 

 krankheiten, 1896, Bd. xxiii. S. 452. 



