476 EXPERIMENT STATION RECORD. [Vol.36 



In the investigations reported Bacillus hulgaricus, Streptococcus hollandicus, 

 and three varieties of Bacterium luctis acidi were used. It was found that the 

 majority of these lactic-acid bacteria develop as readily in milk which is not 

 fresh as in fresh milk. Two of the three strains of B. lactis acidi showed the 

 reaction of Paraschtschuk, one feebly and the other, isolated from Hansen's dry 

 lactic ferment, very distinctly. These species of bacteria coagulate and acidify 

 old milk more rapidly than fresh milk. The different degrees of sensibility of 

 the bacterial reaction in milk of the same degree of freshness render the 

 Paraschtschuk method unacceptable. 



Further researches with Hansen's bacillus show that the increase of protein 

 cleavage products in milk, due to inoculation with peptonizing saprophytes, the 

 addition of peptone, and the action of rennet, augments the acid-forming ability 

 of this microbe. In view of the fact that the preliminary inoculation of fresh 

 milk with a vigorous strain of B. lactis acidi followed by sterilization increases 

 the acidity produced by Hansen's bacillus, it is thought that lactic-acid bacteria 

 in their preliminai-y phase of development in milk cause proteolysis by secreting 

 the proper ectoenzyms. Preliminary inoculation with B. hulgaricus produced no 

 effect, indicating that proteolytic enzyms of different species of lactic-acid bac 

 teria are not of the same order. 



Advantag'es of using milk of low bacterial content in studying the 

 phenomena of lactic fermentation, R. Burri and G. Hohl (ScJnceiz. Zenthl. 

 Milchw., 5 (1916). Nos. 2, pp. 12-lJf; 3, pp. 19-23; abs. in Internat. Inst. Agr. 

 [Rome], Internat. Rev. Sci. and Pract. Agr., 7 (1916), No. 4, pp. 596, 597).— This 

 is a report of the first portion of a series of experiments at the Dairying and 

 Bacteriological Institute of Berne-Liebefeld on the scientific principles under- 

 lying the lactic fermentation test. Milk samples with an average bacterial con- 

 tent of from 200 to 300 per cubic centimeter were obtained from four cows by 

 means of aseptic milking. The experiments extended over three different 

 periods, each of several days' duration. 



The experiments have confirmed the conclusions of others that about one-tenth 

 of the bacterial content of milk immediately after being drawn is derived 

 from the interior of the udder. The species of bacteria were found to vary in 

 different cows, but were always constant for the same cow. Bacterium giin- 

 theri liquefactive in the milk of two cows, white liquefying micrococci for the 

 milk of the third cow, and liquefying micrococci and streptococci in the milk 

 of the fourth were the species found. 



The fermentation test applied to these samples showed that the liquefying 

 B. giintheri is the chief factor exerting an unfavorable influence on the phe- 

 nomena of lactic fermentation. This organism causes the formation of a curd 

 whose degree of consistency is intermediate between that of casein and that 

 of whey-curd. 



These results show that the bacteria of the udder may have injurious effects 

 on the quality of milk and its derivatives. 



A common, but incorrect, statement concerning the number of bacteria in 

 milk, R. S. Breed (Science, n. ser., U (1916), No. 1143, pp. 749, 750).— The 

 author advocates the abandonment of the present custom of referring to agar- 

 plate couuts as showing the number of bacteria in milk, since these counts show 

 only the number of colonies developing on the nutrient medium under tlie con- 

 ditions of incubation used. Studies at the New York Cornell and Geneva ex- 

 periment stations are cited which tend to show that the actual number of bac- 

 teria in milk may be from 2 to 25 times the number of colonies developing on 

 agar plates even after prolonged incubation. 



Cheese factory and creamery instruction and inspection (Agr. Gaz. Canada, 

 S (1916), No. 11, pp. 964-985, figs. 8).— This is a series of articles in which there 



