PATHOGENIC PROPERTIES 185 



Ascertain whether the organism produces enzymes. Does 

 it manifest a proteolytic function, as shown by the 

 liquefaction of gelatin, casein, or blood-serum? Note 

 whether this function is manifested in alkaline or in acid 

 condition of the medium. Does it manifest a precipitating 

 effect (rennet ferment?) upon casein? Note whether this 

 is manifested in alkaline or in acid condition of the 

 medium. Does the organism have the property of breaking 

 up any of the carbohydrates into simpler compounds? Is 

 this alteration accompanied or not by the liberation of gas? 

 If so, ascertain the relative amount of gas formed from a 

 given quantity of carbohydrate. Analyze the gas formed, 

 and state the relative proportion of carbon dioxide and 

 residual (explosive) gas formed. 



Ascertain whether the organism produces indol. Is this 

 substance formed with the simultaneous reduction of 

 nitrates to nitrites? Are the nitrites reduced further into 

 ammonia? 



PATHOGENIC PROPERTIES. 



Ascertain whether any of the animals used for experi- 

 mental purposes are susceptible when inoculated with the 

 organism. Are all species of laboratory animals equally 

 susceptible, or are some immune? Note the size of the 

 dose and the manner of inoculation that gives the most 

 constant and characteristic results. What are the symp- 

 toms and postmortem appearances produced ? What is the 

 location of the organisms in the body of the dead animal? 

 Are they confined to the seat of inoculation, or are they 

 distributed more or less generally throughout the body? 



Note whether the virulence of the organism is maintained 



