Septembeb 3, 1915] 



SCIENCE 



319 



Alkali-forming bacteria are very common in 

 milk, but would rarely be noticed on litmus-lac- 

 tose agar plates. They can be found by inocu- 

 lating into tubes of litmus milk and observing the 

 reaction after 7 to 14 days' incubation at 30° C. 



The alkali-forming bacteria can obtain their ni- 

 trogen from meat juices, peptone, casein, gelatin, 

 and many can also, with few exceptions, use nitro- 

 gen from inorganic salts, such as sodium ammo- 

 nium phosphate and probably all ammonium salts; 

 also from sodium nitrate and nitrite. 



The best source of carbon seems to be the salts 

 of organic acids. 



Since various cultures ferment salts of different 

 organic acids, we hope to be able to classify this 

 group of bacteria on these fermentations. In 

 sugar broths only an alkaline reaction is produced 

 and consequently the sugar fermentation is of no 

 value as a means of classification. 



We believe the fermentation of salts of organic 

 acids will be of great value in the classification of 

 bacteria, particularly soil bacteria, which do not 

 ferment sugars when present in broth. 



Decomposition of Casein in Presence of Salt ty 



Butter Flora: Ghas. W. BEOWisr. 



The casein in butter during storage is slowly 

 broken down into amino-aeids and ammonia. Ni- 

 trogen, as amino-acids and ammonia, in percentage 

 of the total nitrogen in unsalted butter (average 

 of tubs from three creameries) was found to be 

 5.71 per cent, at first and 7.59 per cent, after 240 

 days' storage at 21° F. ; in salted butter from the 

 same three churnings and stored in the same stor- 

 age was found 5.71 per cent, at first and S.19 per 

 cent, after 240 days. And again, in salted butter 

 made from pasteurized and from unpasteurized 

 cream, the percentage (average of 20 tubs) in- 

 creased from 6.24 to 6.86 per cent, for the pas- 

 teurized and from 7.68 per cent, to 8.25 per cent, 

 for the unpasteurized during storage at 0° F. for 

 428 days. 



Pure cultures of twelve different bacteria iso- 

 lated from storage butter when introduced sepa- 

 rately into flasks of sterile separated milk and 

 also into other flasks of the same milk to which 

 was added 5 per cent, sterile salt and incubated at 

 20° C, caused a decomposition of the casein dur- 

 ing 1, 8 and 7 days as follows: The nitrogen (per 

 ceiLt. of total milk) found as caseoses and 

 caseones (average for 12 different bacteria) was 

 0.031 per cent., 0.037 per cent, and 0.054 per cent, 

 in plain milk; and 0.030 per cent., 0.034 per cent, 

 and 0.042 per cent, in milk with 5 per cent, salt; 



the nitrogen found as amino-acids and ammonia 

 was 0.031 per cent., 0.042 per cent, and 0.076 per 

 cent, for plain milk and 0.028 per cent., 0.035 per 

 cent, and 0.041 per cent, for salted milk. 



While the activities of butter flora in the de- 

 composition of casein milk with or without salt 

 can not be considered to parallel their action in 

 butter, yet can we not assume safely that at least 

 part of the casein decomposition in butter is due 

 to the butter flora? 



The Presence of Streptococci in the Milk of Nor- 

 mal Animals: J. M. Sherman and E. G. Hast- 

 ings. 



In many public-health laboratories the routine 

 examination of milk includes tests for strepto- 

 cocci. The supposed relation between udder strep- 

 tococci and septic sore throat in man is the rea- 

 son for making such examinations. 



The examination of the milk from 88 individual 

 animals in four herds demonstrated the presence 

 of streptococci in 38.6 per cent, of the samples of 

 milk. The animals were all free from udder 

 trouble. The examination of the product of twelve 

 herds demonstrated the presence of streptococci 

 in the milk of ten of the twelve examined. In 

 all of the above cases 1/100 c.o. of milk was used. 

 It would seem that the milk of healthy animals 

 frequently contains streptococci at the time it is 

 drawn from the udder, and that before much 

 emphasis can be placed on the detection of these 

 organisms in milk, methods by which harmful 

 types can be differentiated from the harmless ones 

 must be devised. 



The milk of most of the herds examined was 

 used chiefly for the feeding of children. No 

 known eases of trouble have resulted. 



The Refrigeration of a City's Milk Supply: 



Carleton Bates. 



This paper sets forth the plan of a milk cam- 

 paign as conducted by the Bureau of Chemistry, 

 U. S. Department of Agriculture. It further sets 

 forth the results of the bacteriological examina- 

 tions of a city's supply, the causes of the high 

 bacteriological counts obtained, and means em- 

 ployed for remedying the causes. 



The chief cause of the high bacteriological counts 

 was due to non-refrigeration of milk in transit, 

 the average temperature of the mOk upon receipt 

 in the city being about 65° F. This milk was en 

 route from six to twelve hours. 



After refrigeration had been provided by the 

 railroads the milk, at the present time, is being 

 received in the city at about 48° F. 



