1186 Journal of Applied Microscopy. 



CURRENT BACTERIOLOGICAL LITERATURE. 



H. W. Conn. 



Separates of papers and books on bacteriology should be sent for review to 

 H. W. Conn, Wesleyan University, Middletown, Conn. 



Jensen. Studien uber die Enzyme im Kase. -pj^g question whether various fermen- 



Cent. f. Bac. II. 6: 734, 1900. . ^ . 



„ „ , . r , T- tative processes in nature are to be 

 Babcock and Russell. Relation of the Enzymes 



of Rennet to Ripening of Cheddar Cheese. ascribed properly tO the action of 



Cent.f. Bac. II. 6: 817,1900. (See also sev- micro-organisms or to the action of 



enteenth annual report of Agri. Expt. bta. of '^ . 



Wis.) enzymes, has, in late years, become a 



Babcock and Russell. Causes Operative in the somewhat burning one with our bacteri- 

 Formation of Silage. Seventeenth An. Rep. ologists and chemists. In large degree 

 of Agri. Expt. Sta. of Wis., 1900. ^ . , . ,, . , 



,. , ^ , the question reduces itself simply to 



Behrens. Ueber die oxydierenden Bestand- 



theile und die Fermentation des Deutschen determining whether the enzymes, 

 Tabaks. Cent. f. Bac. II. 7 : i, 1901. which are the direct cause of the action, 



are produced by bacteria or from some other source. The four papers here 

 referred to discuss different aspects of this problem. It has been shown by 

 Babcock and Russell that fresh milk contains an enzyme which they have named 

 galactase. They believe that this enzyme, rather than micro-organisms, plays 

 the important part in the ripening of cheese. The first of the articles here 

 referred to contains an especially careful series of experiments to test this con- 

 clusion. As the result of a long series of most careful experiments, Jensen 

 concludes, in brief, that in the ripening of soft cheeses the effect is produced, 

 (1) by enzymes which are produced by yeasts and bacteria growing on the 

 surface of the cheese ; and (2) by enzymes in the center of the cheese which are 

 not derived from bacteria growth, but rather from the rennet which was added 

 to curdle the casein, the enzyme in this case being pepsin. The ripening of 

 hard cheeses depends partly upon the action of an enzyme produced throughout 

 the mass as the result of bacteria, and partly, especially in the early part of the 

 ripening, upon the galactase, which, as Babcock and Russell have shown, is 

 present in the fresh milk. 



In the second article Babcock and Russell test, by an entirely different line 

 of experiments, the question whether the pepsin present in the rennet has an 

 important agency in the ripening of cheese. The conclusion they reached is 

 essentially identical with that of Jensen, namely, that the ripening of cheese is 

 dependent in considerable degree upon the pepsin present in the rennet. The 

 agency of bacteria in the ripening of cheeses is not especially studied by 

 these authors. 



The third paper records a series of experiments to determine whether the 

 production of silage is, as has previously been believed, the result of the growth 

 of micro-organisms. The authors reached the conclusion that micro-organisms 

 have nothing whatsoever to do with the production of normal silage. Both the 

 initial heating and the subsequent ripening of silage are due to entirely different 

 agents. The production of silage, the authors believe, is due, (1) to the 



