800 EXPERIMENT STATION RECORD. 



The bacteriological examination of milk, A. C. Houston {London: P. S. King 

 & Son, pp. 48; rev. in Brit. Med. Jour., 1906, No. 2356, pp. 452, 453).— -The author 

 ascertained the amount of dirt in milk before and after centrifuging, and made bac- 

 teriological examinations of 20 samples of milk from each of five sources. The 

 sources of contamination of milk are discussed and the desirability of establishing 

 temperature and bacteriological standards for milk is considered. 



In order to be free from objection, milk, according to the author, should fulfill 

 the following conditions: One cc. should not show the presence of Bacillus enteritidis 

 sporogenes; 0.001 cc, the presence of B. coli; nor 0.0001 cc, the presence of strepto- 

 cocci. The primary sediment after 24 hours should not exceed 100 parts per million, 

 nor the secondary sediment after centrifuging 50 parts per million. The problem of 

 improving milk supplies is discussed and several reforms considered practicable are 

 enumerated. 



Lactic-acid bacteria, W. M. Esten (Abs. in Science, n. ser., 23 (1906), No. 580, 

 p. 210). — Studies have been made of the lactic-acid bacteria isolated from samples of 

 milk received from nearly every section of the United States and Canada. 



Two distinct groups of lactic-acid bacteria have been found, (1) gas-forming bac- 

 teria, (2) nongas-forming bacteria. The first group consists of Bacillus coli communis 

 and Bacterium lactis aerogenes, which is considered identical with the Bacillus acidi 

 lactici of Hueppe. The second group, in the opinion of the author, consists of only 

 one species of bacterium with its varieties, namely, Bacterium lactis acidi of Leichman. 

 The first group is aerobic and the second facultative anaerobic. 



Milk not containing B. lactis acidi is considered a dangerous product if kept for any 

 length of time, inasmuch as it then becomes a good medium for the growth of all 

 kinds of putrefactive bacteria and disease germs, while milk containing this organism 

 soon becomes nearly free from other forms. 



Kinds of bacteria concerned in souring of milk, P. G. Heixemaxx (Abs. in 

 Science, n. ser., 23 (1906), No. 580, pp. 211, 212).— The author believes that all so- 

 called lactic-acid bacteria belong to two groups, the colon aerogenes group and the 

 streptococcus group, and states that this arrangement is arrived at by a comparative 

 study of culture characteristics of pathogenic, sewage, fecal, and milk streptococci. 



The ordinary bacteria producing lactic fermentation are stated to be Bacillus aero- 

 genes lacticus and Streptococcus lacticus either alone or in cooperation. Bacillus coli and 

 peptonizing bacteria it is believed may also participate in the souring of milk. The 

 gas-producing organism is present in large numbers in initial stages but is ultimately 

 stopped by the development of the streptococcus. Lactic-acid bacteria are believed to 

 be of intestinal origin, gaining access to milk with particles of cows' feces. 



Since Streptococcus lacticus is invariably present in fresh milk collected with good 

 precautions it is believed that the sanitary significance of streptococci in market milk 

 needs further investigation. 



A note on the indol-producing bacteria in milk, S. C. Prescott (Abs. in 

 Science, n. ser., 23 (1906), No. 580, %>P- 212, 213). — In studying the relation between 

 the occurrence of indol-producing bacteria and the total number present in milk, 

 bacteriological examinations were made of 524 samples collected from 175 different 

 farms. The results obtained with 278 samples are tabulated. 



Of 13 samples containing above 1,000,000 bacteria per cubic centimeter, 9 samples 

 or 70 per cent showed the presence of indol; of 2 samples containing between 500,000 

 and 1,000,000, 1 sample or 50 per cent showed the presence of indol; of 34 samples 

 containing between 100,000 and 500,000, 14 samples or 41 per cent showed the pres- 

 ence of indol; of 229 samples containing between 25,000 and 100,000, 32 samples or 

 14 per cent showed the presence of indol; and of 133 samples containing 25,000 or 

 less, 17 samples or 12 per cent showed the presence of indol. 



Bacteriological studies of some milk samples of abnormal properties, 

 R. Burri and M. Duggeli (Centbl. Ball, [etc.], 2. Abt., 15 (1906), No. 22-23, pp. 



