DAIRY FARMING DAIRYING. 291 



open vessels for a consi(lera))le time, it is exposed to infection from the air; and if 

 the ])utter is washed with unboiled water there is danger of water infection. The 

 whole object of pasteuiization can, therefore, be defeated by improper snbseijuent 

 treatment. Absolute safety recjuires that the pasteurized cream should be cooled in a 

 closed a|)paratus with the aid of sterilized air, the cream vat kept well covered, and 

 the l>utter washed only with boiled water. 



Lactic acid ferments and the ripening- of cheese, E. von Frkudenreich 

 {Ccidhl Bakt. u. Par., 2. Abt., S {1902), Nos. 21, pp. 674-681; 22, pp. 705-711; 2S, 

 pp. 735-738; Lanrhr. .Tahrh. Srliirciz, 16 {1902), No. 3, pp. 91-104; Jic'. ('hi. Lait, 1 

 {1902), Nos. 13, pp. 289-295; 14, pp. 313-319; 15, pp. 340-346) .—The author sought 

 to obtain decisive proof of the causal relation of lactic acid bacteria to the ripening 

 of cheese. The milk used in the experiments was drawn with thorough aseptic pre- 

 t'autifins and made into P]mmenthaler cheese according to tlie usual methods. Not- 

 withstanding the care taken the milk was found to contain a maximum of 680 and an 

 average of 2o0 bacteria per cubic centimeter. At the same time milk drawn without 

 asceptic precautions contained as high as 11,250 bacteria per cubic centimeter. 

 Lactic acid bacteria were almost invariably absent in the freshly drawn milk. 

 Experiments to ascertain the source of the lactic acid bacteria showed their absence 

 in outdoor and laboratory air, spring water, soil, and fecal matter; and their presence 

 in the air of the stable, dust and hair from the cows, and litiuid manure. The 

 bacteria regularly met with in the freshly drawn milk were mainly licjuefying and 

 nonli(inefying micrococci. 



In all 35 experimental cheeses were made, each from 14 liters of milk. Hansen's 

 rennet tablets were used in all cases except for cheeses ripened with lactic acid 

 bacteria, when natural rennet rich in lactic acid bacteria was employed. Six 

 cheeses were made without the addition of cultures and were used as controls. The 

 other cheeses were made with the addition of liquefying micrococci, lactic acid bac- 

 teria, and Bacillus nobilis, either in pure cultures or mixed. The cheeses were judged 

 by a commission and subjected to bacteriological and chemical examination, the 

 results of which are considered by the author as showing that lactic acid bacteria 

 play the principal role in the ripening of cheese. The control cheeses did not 

 undergo normal ripening especially as regards flavor. The favorable action of the 

 lactic acid l)acteria was most marked when they were added in the form of natural 

 lennet. The liquefying micrococci in the absence of lactic acid bacteria gave the 

 cheese a bitter flavor, but in the presence of lactic acid bacteria their development 

 soon ceased. B. nohilis adiled in pure cultures did not develop in the presence of 

 lactic acid bacteria, which was also the case when Tyrogen alone was used. Pure 

 cultures of B. vdhilJs in the absence of lactic acid bacteria gave the cheese a repulsive 

 odor. Several other experiments are noted briefly, which likewise demonstrate, 

 according to the author, that Tyrogen does not exert the least influence in the ripen- 

 ing of soft cheese. 



Investigations on the presence and development of Tyrothrix bacilli in 

 Emmenthaler cheese, Gekda Tkoili-Petkksson {Latidw. Jalrrli. Sr]iiceiz, 16 {1902), 

 No. 7, j>p. 26-3.'; Aim. Afjr. Suisse, 3 {1902), No. 1, pp. 5-12). — Bacteriological studies 

 here reported leil to the conclusion that the number of Tyrothrix bacilli in (theese ia 

 iiL^ignificant com]tared with the total number of bacteria or even with the nmnber 

 of other liquefying bacteria present, and that there is no increase in the number of 

 Tyrothrix bacilli in cheese. On the contrary, when pure cultures of Bacillus nobilis 

 were used in large quantities the bacilli dnninished rapidly during the first two days. 



Acid and rennet producing bacteria in milk, C. Gorini ( Laridw. Jahrb. Schweiz, 

 16 {1902), No. 1, pp. 22-25; Ceiitbl. Bakt. u. Bar., 2. AbL, 8 {1902), No. 5, pp. 137- 

 140; Ann. Ayr. Suii^.w, 3 {1902), No. 1, pp. 1-4). — The author's studies indicated the 

 presence in milk of micrococci producing acid and rennet and capable of peptonizing 

 casein in an acid medium, 



