ABSTRACTS 87 



Produces a red pigment at room temperature. Rapidly liquefies 

 gelatin and produces ammonia. Is a facultative anaerobe. Group 

 number is 221.1012701. 



On the Correlation of the Voges-Proskauer and the Methyl Red Reaction. 



Max Levine. 



The methyl red reaction of Clark and Lubs was suggested as a rel- 

 atively quick and simple routine test for the differentiation of the colon- 

 aerogenes group of bacteria. This test correlates strikingly with the 

 accurately determined gas ratio. It is desirable that the methyl red 

 reaction should also be correlated if possible with some previously 

 employed test in order that the valuable work of the Department 

 of Agriculture may be adequately compared with the numerous pre- 

 vious investigations. 



From a study of 187 coli-like bacteria, 31 of which were obtained 

 from other investigators and 156 isolated from raw and septic sewage 

 and from the feces of the cow, pig, horse, sheep, and man, it was found 

 that only those organisms which gave the Voges-Proskauer reaction 

 were alkaline to methyl red. One hundred and fifty-nine of the organisms 

 were negative to the Voges-Proskauer test; these were all acid to 

 methyl red, while all of the 28 which reacted positively to the Voges- 

 Proskauer test were alkaline to methyl red. It was also observed that 

 although 23 per cent of the organisms isolated from sewage gave these 

 two reactions (methyl red alkaline, V.P. + ), no such organisms were 

 isolated from the feces of the horse, cow, pig, sheep, and man. 



The scarcity of organisms giving the Voges-Proskauer reaction in 

 human feces is dwelt upon by MacConkey and also pointed out by 

 Clemesha. Coli-like bacteria which give this reaction are character- 

 istically of non-fecal origin. They resemble, in many other characters 

 the Bacillus aerogenes (Escherich) and probably represent soil forms. 



TECHNIQUE 

 Under Supervision of Jean Broadhurst 



Acidity of Media. H. A. Notes. 



Media for bacteriological purposes are standardized to definite de- 

 grees of acidity or alkalinity. There are several factors which may 

 affect the accuracy with which the reaction of the media is determined. 

 The paper, as presented, took up several of these factors and gave 

 results of experimental work carried out in the Horticultural Research 

 Chemistry and Bacteriology Laboratories of the Purdue Agricultural 

 Experunent Station. The following conclusions were reached: 



1. Agar-agar and gelatine should be the best obtainable. A grade 

 of each, such that unfiltered solutions contain no visible solid matter, 

 is obtainable. 



2. Only necessary chemicals of the highest purity should be used. 



3. The resulting products of reactions that will occur when a number 

 of compounds are put together should be understood before one at- 

 tempts to make combinations of them in a medium. 



