CHANGES PRODUCED BY A SAPROPHYTIC ANAEROBE 397 



changes, deop-scated enough to be detected l\v the ordinary 

 chemical methods. After growth has been estabUslied they may 

 then utilize some other clement in the medium as their chief 

 source of energy. It may bo noted that the anaerobes studied 

 by us grow verj' well in a solution of peptone and water. 



These organisms could not utilize simple nitrogenous foods to 

 any extent; nitrates, ammonia salts, urea and asparagin in a sim- 

 ple solution or in the presence of glucose give practically no de- 

 velopment. They were able to grow well upon simple peptone 

 solutions and attack the albumins of egg-white, blood serum, 

 milk and meat, and also liquefy gelatin, either in the presence or 

 absence of glucose. The changes in all cases are deep-seated 

 since gas, volatile fatty acids, amino-acids and ammonia are 

 formed from all of these media in fairly large amounts. Traces 

 of hydrogen sulphide are also found in some of the meat cultures. 



The proteolytic action is tryptic in nature, since it does not 

 take place in a medium acid to litmus and is more active in a 

 medium neutral to phenolphthaline than in one neutral to litmus. 



Gas production. In cases in which large vohuucs of gas were 

 present we considered that active fermentation had occurred, and 

 this was correlated with the results of the fermentation tube tests. 

 From these results, we are safe in considering that an anaerobe 

 has attacked a carbohydrate vigorously only when it produces 

 more than 1 per cent of gas in the closed arm of the fermentation 

 tube, and a reaction distinctly acid to brom-thymol-blue. A 

 bubble of gas might be taken to indicate slight fermentation of 

 the carbohydrate, if it were present in the tube containing car- 

 bohydrate medium but not in a tube containing the media minus 

 the carbohydrate. We have made as many as twenty parallel cul- 

 tures of these anaerobes and treated all exactly alike; in some tubes 

 there may be as much as one per cent of gas, in others a small 

 bubble, and in others none at all, and all containing about an 

 equal amount of growth. Since irregularities are unavoidable 

 with these organisms, some arbitrary hmit should be set. In this 

 work we recorded a positive fermentation when more than one 

 per cent of gas was formed and a questionable result when less 

 than that amount was present if there were no marked change in 

 the reaction. 



