and Laboratory Methods. 2347 



CURRENT BACTERIOLOGICAL LITERATURE. 



H. W. CONN, Wesleyan University. 



Separates of Papers and Books on Bacteriology should be Sent for Review to H. W. Conn, 

 Wesleyan University, Middletown, Conn. 



Boekhoet and Ott de Vries. Ueber die Reifung These authors have returned again to 

 der Edamer Kase. C. f. B. ii, vii, p. 187, the question whether the ripening of 

 ^^° ■ cheese is due to bacteria, as bacteriol- 



ogists have beUeved for some time, or in large degree to enzymes, as has been 

 claimed by Russell and Babcock. They had previously shown that it was diffi- 

 cult to get cheese to ripen without the presence of bacteria, and the experiments 

 which they have now conducted have obtained two results. First, they have 

 isolated two very important bacteria from Edam cheese which they regard as 

 contributing largely to the ripening ; secondly, they have experimented with 

 cheese made from milk obtained under special precautions. They attempted 

 first to obtain directly from the cow milk which was sterile, but found this an 

 impossibility. They then adopted the plan of thoroughly washing the ani- 

 mals with a disinfectant solution, and drawing milk under special precau- 

 tions in closed pail under conditions where the bacterial contamination was 

 reduced to its minimum. This was done by having a long spout leading from 

 the side of the pail and ending in an open funnel at the same distance from the 

 closed pail. Under these conditions they obtained milk which was, not indeed 

 sterile, but had only an exceptionally small number of bacteria. With such milk, 

 which they called aseptic milk, they made cheeses and found that under these 

 conditions the ripening of the cheese did not occur. Such milk of course con- 

 tained all of the natural enzymes and differed only from normal milk in lacking 

 bacteria, and they therefore reached the conclusion that, in addition to the action 

 of galactase, the ripening of cheeses is in reality due to the action of bacteria. 



Kozai. Weitere Beit.age zur Kenntniss der This author, a Japanese, who has pre- 

 naturlichen Milch gerinnung. Zeit. f. Hyg. viously given useful papers upon milk 

 xxxviii, ^87, I go I. • 1. -u ^ c ..u 



-^ ' ^ souring, contributes a further paper 



upon the same general subject, for the purpose of verifying previous conclusions 

 and explaining the contradictions of others. The important conclusions which 

 he reaches are as follows : First, in spontaneous milk souring there is produced 

 lactic acid, alcohol, acetic acid and salicylic acid. Second, the temperature at 

 which the milk is kept has a great influence upon the kind of fermentation that 

 takes place. In the slow processes of souring there is a more profound decom- 

 position of albuminoids and non-nitrogenous substances than when the process 

 goes on rapidly. In spontaneous milk souring there are three chief species of 

 bacteria concerned. The most important of which he calls B. acidi paralactici, 

 which is the same species as described by several others under different names. 

 A second species is B. acidi IcEvo/acfid, while a third is a micrococcus. The 

 coli bacillus is also present and sometimes aids in the process. The second of 

 the three species belongs to the aerogenes group and it produces left handed 

 milk acid and a small quantity of alcohol, together with some acetic and salicyUc 

 acid. The results thus obtained are in essential agreement with those obtained 

 by students of milk bacteriology in this country. The chief species described 

 by Kozai is apparently identical with the B. acidi lactici of Esten, which is the 

 most common cause of milk souring in America. h. w. c. 



