18 



L. F. RETTGER, N. BERMAN AND W. S. STURGES 



ing contrast to the rest. The most plausible explanation of the 

 proteolytic action in these tubes is that these organisms pro- 

 duced a very active proteolytic enzyme early in the course of 

 their growth on the slant agar, so that sufficient enzyme was 

 introduced into the test medium along with the bacteria to bring 

 about cleavage of the albumin and thus prepare it for nitrogen 

 assimilation by the bacteria. These tests are being repeated. 



In all of the experiments except the three just commented 

 upon there was no visible indication of bacterial disintegration 



TABLE II 



Control experiments. Enumeration of bacteria in inoculated medium containing 

 heated (coagulated) egg albumin and 1 per cent of peptone 



Note: XX indicates too many plate colonies to count. 



In all of the experiments recorded in tables I and II the test medium con- 

 tained the following inorganic salts: Sodium chloride 0.5 per cent, sodium sul- 

 phate 0.2 per cent, calcium chloride 0.1 per cent, and acid potassium phosphate 

 0.1 per cent. 



of the egg albumin. In fact, the liquid portion of the medium 

 remained clear and colorless, and the medium could not be dis- 

 tinguished from the uninoculated tubes, either by its appear- 

 ance to the naked eye or by the odor. Control tubes contain- 

 ing the same ingredients plus 1 per cent peptone rapidly under- 

 went marked change. The protein became involved and, in the 

 tubes containing gelatin-liquefying organisms, was gradually di- 

 gested. In every instance the liquid part of the medium soon 

 became turbid, and frequently more or less colored (see Table II). 



