16 



H. J. Sears 



the technic employed in the original experiments ; namely, that of inocu- 

 lating a large volume of the medium and withdrawing samples day by 

 day with a sterile pipet. It was further determined also to study the 

 effect of glucose on amino-acid-production. It had been shown clearly 

 by Kendall and his co-workers that this carbohydrate very considerably 

 reduced the rate of ammonia- formation by most micro-organisms. It 

 was a matter of interest to know also whether it would reduce amino- 

 acid-production. 



TABLE 5 



The Production ok Ami.noacid and Ammonia by B. Proteus-Vulgabis in a Meat-Extract 



Peptone Solution 



Seven organisms were investigated in this respect. The exact technic of 

 the experiment was as follows. A large amount of a 2% peptone solution con- 

 taining 0.5% NaCl was prepared and divided into 2 equal portions, to one of 

 which was added approximately 1% of pure glucose. The media were then 

 placed in 500-c.c. flasks, 300 c.c. to each. To each of the flasks containing 

 glucose a small amount of CaCos was added. All the samples were sterilized 

 together in the autoclave for 10 minutes under an extra pressure of 15 lb. 

 They were all inoculated at Zl C. in the same incubator. The incubator was 

 kept saturated with moisture to prevent evaporation. Samples, 15 c.c. in amount, 

 were withdrawn at intervals as indicated in the tables, and were subjected at 

 once to a half hour's heating in steam at 100 C. This would, of course, not 

 sterilize the cultures of B. subtilis, but as the analyses were usually completed 

 on the same day that the samples were taken (otherwise the samples were kept 

 in the ice chest), it is not probable that any error was introduced by that fact. 



Tables 6 to 12 inclusive give the results of the analyses of these 

 samples. Charts 3 to 5 represent the same results in the form of 

 curves. 



