680 EXPERIMENT STATION RECORD. [Vol.43 



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straining milk sent to the District of Columbia were collected after the usual 

 farm cleaning and examined bacteriologically. Counts of total bacteria ranged 

 from 6,000 to 430,000,000 per 0.01 sq. ft. Colon organisms and streptococci 

 were numerous in niaiiy cases. 



Number of bacteria on the lips of milk bottles and their significance, 

 R. S. Deaestyne and C. L. Ewing {Amer. Jour. Pub. Health, 10 (1920), No. 6, 

 pp. 533-535). — Counts are recorded of the number of bacteria collected (by 

 swabbing) from the rims of 50 bottles of pasteurized milk delivered to con- 

 sumers in Baltimore, Md., and 50 bottles of raw milk delivered in Alexandria, 

 Va. Half the Baltimore samples bore over 5,000 bacteria, and half those from 

 Alexandria over 50,000 bacteria. The hands of deliverymen, dust from the 

 air, flies, cats, and dogs are listed as sources of contamination. 



The accuracy of bacterial counts from milk samples, R. S. Breed and 

 W. A. Stocking, je. {New York State Sta. Tech. Bui. 75 (1920), pp. 3-97).— 

 Three series of parallel bacteriological analyses of milk samples by workers at 

 Geneva and Ithaca are reported. Results from two of the series have been 

 noted from a preliminary report (E. S. R., 38, p. 579). In the third series, 

 which was mainly a repetition of the second (the samples being inoculated 

 with a colon organism), a still greater uniformity was secured both in the 

 plate counts and in the direct counts with a microscope. 



There was a close agreement between the microscope counts of isolated groups 

 (clumps) of one or more organisms and the agar plate counts. "The average 

 number of individuals in the clumps of bacteria present commonly varied 

 between two and six, but at times (when streptococci were present) greatly 

 exceeded these numbers. As the data indicate that the clumps are only very 

 poorly broken apart in the processes ordinarly used in preparing dilution waters, 

 the plate counts did not represent the full number of bacteria present." 



The lactic acid bacteria, S. O. Jensen {K. Danske Vidensk. Selsk. Skr., 

 Naturvidensk. og Math. Afd., 8. ser., 5 {1919), No. 2, pp. 81-196, pis. 5i).— This 

 is an elaborate monograph (written in English) on the lactic acid bacteria, 

 emphasizing particularly the cultural features and the sources of energy and 

 nutriment utilized by the species considered. It is based on 10 years' work 

 and the cultivation of 330 strains isolated from dairy products, animal feces, 

 and plant materials. 



The lactic acid bacteria are considered a natural group composed of immotile, 

 sporeless. Gram-positive, rod- and sphere- forms, which are lacking in catalase 

 and which in fermenting sugar form chiefly lactic acid. Whether the lactic 

 acid is dextrorotary or laevorotary is found to be an important diagnostic 

 character, since the optical properties are not influenced by the kind of sugar 

 fermented. Five genera (Thermobacterium, Streptobacterium, Betabacterium, 

 Streptococcus, and Betacoccus) comprising 22 species are recognized as true 

 lactic acid bacteria, and two genera (Microbacterium and Tetracoccus) are 

 regarded as closely related. Except for Streptococcus, which is redefined, 

 these generic names are new. A number of changes in the designation of 

 species are also introduced. 



The true lactic acid bacteria are incapable of breaking down uncombined 

 amino acids, and relatively few have marked proteolytic action. " The cocci 

 which split up casein decompose it gradually through peptones to amino acids; 

 the casein-splitting rod forms, however, peel off the mono-amino acids from 

 the casein molecule without previous formation of peptone. From the pep- 

 tones, the lactic acid bacteria appear to form a quantity of polypeptids, which 

 are not precipitated by phosphotungstic acid." ^i 



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