April 7, 1911] 



SCIENCE 



541 



agencies in the reddening of prepared salted fish. 

 During the seasons of 1907 it was predominant on 

 the samples examined, although it is possible to 

 conceive that varying seasonal conditions of dif- 

 ferent Hummers may change the predominant form 

 so that some other one of the various microorgan- 

 isms as the causal factors of ' ' red fish ' ' may 

 become the most destructive ones. This question 

 is worthy of further study. 



Bacterial Flora in Milk: H. W. Conn. 



A general resume of the present status of dairy 

 bacteriology was furnished by this paper; and it 

 also touched upon the significance of bacteriology 

 ia the control of municipal milk supplies. (Sec- 

 retary.) 

 Belation of Form of Milk Pail to Germ Content 



of Milk: H. A. Harding and J. K. Wilson. 



The first important infection of milk occurs 

 during the act of milking. 



Ordinary milk paUs have open tops, 12 or more 

 inches in diameter. Many improved paUs have 

 been suggested, but few have been favorably re- 

 ceived by dairymen. 



The leading causes for rejection are the exces- 

 sive height of the pails and the inconvenient size 

 and shape of the opening for receiving the milk. 



Tests of various pails indicated that a success- 

 ful pail should not be over 12 inches high and 

 should have an opening of approximately 25 

 square inches. An oval or elliptical opening is 

 more convenient than a round one of the same 

 area. 



Stocking found that the use of cloths or mechan- 

 ical strainers on pails was not desirable and that 

 the relative efficiency of small-topped paUs was 

 greater under poor dairy conditions. 



Under high-grade dairy conditions when a good 

 small-topped pail was contrasted with an ordinary 

 18-inch open pail the reduction in germ content 

 was more than 50 per cent. As such a pail is as 

 convenient to use and practically as cheap as an 

 ordinary pail, there seems to be no reason why it 

 should not be generally adopted. 

 The Influence of the Products of Lactic Organ- 

 isms upon Bacillus typhosus: Z. Northeup. 



This study was taken up first from the stand- 

 point of the longevity of B. typhosus in sour milk. 

 Previous investigations show that the typhoid bac- 

 teria in infected milk are generally all killed 

 within twenty-four hours after the milk has 

 reached 0.4 per cent, lactic acid. 



Several widely varying types of lactic organisms 

 were obtained from various sources for this study; 



B. typhosus, from the laboratory stock culture. 

 The typhoid bacteria and a lactic-acid producer 

 were grown together in sterile milk after the milk 

 had soured; the combined culture was plated at 

 intervals, a special plating medium was used in 

 two succeeding tests for differentiating the typhoid 

 and lactic organisms; one lactic only was inhibited 

 by the bile agar used as a differentiating medium. 



Assuming that it is the products of the lactic 

 bacteria and not the bacteria themselves which 

 exert the inhibitive influence upon the typhoid 

 bacteria, the plan was formulated of growing the 

 typhoid bacilli in their products alone. The lac- 

 tics were grown in lactose broth, allowed to pro- 

 duce an amount of acid, then filtered through a 

 Chamberland "F" bougie. As a result of these 

 experiments, it was found that a certain amount 

 of the acid produced by the typical lactic organ- 

 isms has greater germicidal properties than the 

 same amount produced by any other type of lactic 

 organism. The typical lactic kills B. typhosus at 

 + 37° acid or 0.3 per cent, lactic acid whOe the 

 acid made by B. tulgaricus and another strong 

 acid-producer reaches nearly twice 0.3 per cent, 

 lactic acid in the lactose broth before the typhoid 

 organisms are killed. 



A comparison was made establishing the rela- 

 tive amount of acid produced in lactose broth and 

 milk by lactic organisms. According to these re- 

 sults, + 37° acid, the minimum inhibitive acidity, 

 produced by No. 2 in lactose broth, corresponds 

 to ^- 80° acid or 0.72 per cent, acid in milk. 



Summarizing, if strong lactic organisms are 

 present in large numbers in infected milk, it may 

 be definitely stated that all typhoid bacteria will 

 be killed when the acidity in the milk reaches 0.72 

 per cent, lactic acid. 

 The Use of Fermentation Tests in the Study of 



the Lactic Bacteria: L. A. Eogers. 



It was foimd that the characters used in de- 

 scribing the lactic bacteria are not distinctive or 

 are too variable to separate this group into sub- 

 groups. 



The curdling of milk is especially variable and 

 uncertain. 



The fermentation of various test substances 

 was found to be constant and, when properly cor- 

 related, to indicate natural grouping. 



By means of these tests it was possible to sepa- 

 rate the 150 cultures studied into three groups. 

 Each of these groups was distinguished by fer- 

 menting or failing to ferment certain groups of 

 test substances. 



