17 



Summary of Constancy or Varial^ility of Reactions. 



A. For B. typhosus : — 



1. Fermentation test. Constant (Burri and Stntzer 



have shown gas formation). 



2. Indol reaction. Shght indication in one case. 



3. Milk Coagulation. SHght clot in one case. 



4. Potassic iodide j^otato gelatine. Characteristic 



invariably, very little use as a separating medium. 



5. Potatoes. Constant with usual precautions. 



6. Beaction in gelatine. Marked differences of rate 



of diffusion. 



B. For B. coli .•— 



1. Fermentation. Rate of gas formation variable, 



otherwise constant. 



2. Indol reaction. Reaction not constant. 



3. Milk coagulation. Rate variable. Constant with 



us, with others not constant. 



4. Potassic iodide potato gelatine. Abundant growth. 



5. Behaviour in gelatine. Diffusion very variable, 



in many cases less rapid than B. typhosus. 



6. Motility. Very variable. 



