510 Bulletin 167 



through a Pasteur filter. Portions of 50 cc. each were removed 

 to sterile flasks by means of sterile pipettes and inoculated with 

 the organism. The cultures were held at 25 ° C. and tested 

 for proteolytic action at intervals from 10 to 44 days, always 

 with negative results. The test was made by adding- to the 

 culture in the flask 75 grams of ammonium sulphate, heating in a 

 water bath at 6o° C. for 30 minutes to precipitate all proteids 

 except peptones and propeptones, filtering, rendering the filtrate 

 strongly alkaline with potassium hydroxid and testing with a 

 few drops of a 1% solution of copper sulphate. 1 



Production of diastolic ferments. — A thin starch paste to 

 which was added 2' ", of sugar free thymol was prepared and 

 added to equal parts of 10 day old broth cultures. After in- 

 cubation at 25 for 6 to 8 hours the solution was filtered and 

 tested for reducing sug"ar with Fchling's solution. The results 

 were negative. 



Production of invertase. — A solution containing 2 r r of cane 

 sugar and 2% of phenol was prepared for the purposes of 

 tin's test. Kqual quantities of 10 day old broth cultures of the 

 organism and this solution were thoroughly mixed and left in 

 the incubator over night. The unclarified solution when tested 

 with Fehling's solution gave a pronounced change of color with 

 a variable amount of copper precipitate, but the reaction was 

 so far from characteristic that a check upon the work was 

 desired. It is customary in analysis of solutions for invert 

 sugars to clarify with some substance, such as neutral lead ace- 

 tate or copper sulphate, before proceeding with the analysis. 

 In the use of lead acetate it is important to avoid a large ex- 

 cess and it is necessary to remove the slight excess used by pre- 

 cipitation with calcium oxalate before proceeding with the Fehling 

 test. In order to determine the influence of clarification of 

 bacterial cultures before running the Fehling test the following 

 solutions were prepared : 



1 Salkowski and Orndorff, loc. cit., pp. 15 and 40. 



