BACTERIUM AEROGENES. 221 



and of coagulating milk are gradually lost after long culti- 

 vation upon gelatin or agar. 



Upon nutrient media free of sugar, there is a slight pro- 

 duction of indol, but none of H 2 S. 



Distribution. — Constantly cultivated from sour milk 

 by Hiippe in Berlin, and by his pupils with slight modi- 

 fications (consult Scholl). In Wiirzburg, since 1888 

 (compare Dissertation by Joh. Claus, Bakteriologische 

 Untersuchung der Milch im Winter 1888-89 in Wiirz- 

 burg), we have never failed to find the organism in milk 

 which had soured spontaneously and naturally, and until 

 recently we had no doubt that it was the most important 

 producer of lactic acid in milk, as Hiippe assumed. Milk 

 which has soured spontaneously contains, in Wiirzburg, 

 considerable quantities of volatile acid. As soon as possi- 

 ble the question as to the most important cause of lactic 

 acid fermentation will be restudied in Wiirzburg. Com- 

 pare page 224. 



Demonstration and Differential Diagnosis. — As dif- 

 fering from Bact. Giintheri, the Bact. acidi lactici grows 

 well upon the ordinary nutrient media, and produces gas 

 vigorously. As regards the staining by Gram's method, 

 variations occur. In order to bring the findings into a 

 scheme we call the forms not stained by Gram's method 

 Bact. lactis aerogenes (see below), and leave the question 

 open as regards the kind of relationship existing between 

 these "species." 



Bacterium aerogenes. 1 (Kruse.) L. and N. 



Synonyms. 2 — Bacterium lactis aerogenes Escherich, Ba- 

 cillus aerogenes Kruse. 



Literature. — Escherich, Die Darmbakterien des Sauglings, 1886, 

 page 57. 



1 A Bact. lactis aerogenes obtained from Krai presented from 1 to 3 

 irregularly arranged, long flagella, and was thus, according to our 

 ideas, a typical Bact. coli. It also produced indol very vigorously. 



2 We cannot understand how Kruse designates the Bact. acidi lac- 

 tici as a variety of the Bact. aerogenes, which was described many 

 years later. If one name is to be eliminated, according to priority, it 

 must unquestionably be that of Bact. aerogenes. 



