DAIRY FARMING — DAIRYING. 279 



No. 9, p. 554). — This includes an analysis of the various fatty acids found in 

 human milk and a comparison witli cow's milk. 



A study of the udder flora of cows, H. A. Harding and J. K. Wilson (New 

 York State Sta. Tech. BuL 27, pp. 3-.'iQ) .—This is a study of the quantitative 

 relationships of the bacterial flora of 1.274 samples of milk and the qualitative 

 relationships of about 900 samples. The samples were carefully milked Into 

 sterile test tubes and exposed to a minimum amount of contamination. 



" Bacteria were most abundant in the first few streams of foremilk, were 

 distinctly less abundant during tlie main portion of the milkinf;. and again 

 became more abundant in the strippings. The germ content was found to be 

 unequally distributed in the udder, the back quarters having about ?> limes as 

 many germs per cubic centimeter as the fore quarters. The average of 1.230 

 samples was 428 per cubic centimeter. The connection between the period of 

 lactation and the germ content was not very marked. The colostrum showed 

 a slightly higher and the milk of the twelfth month a slightly lower content 

 than the Intervening periods. The age of the cow likewise was not found to 

 exert any appreciable effect upon the germ content of the udder. The kinds 

 of organisms present in over 900 samples of milk were studied and 71 groups 

 described as members of the udder flora. No organisms producing spores and 

 no motile forms were found. Seventy-five per cent of the forms were micro- 

 cocci but only 2 streptococci were isolated. The need of free oxygen was 'so 

 great that SO per cent of the forms were not able to produce turbidity in the 

 closed arm of the fermentation tube. Gelatin was liquefied by 55 per ceL.t of 

 the forms and digestion of milk was evident in cultures of about one-half of 

 these forms, the remainder probably liquefying too slowly to be determined by 

 this comparatively crude method. No gas was formed in fei'mentation tubes 

 in the presence of dextrose, lactose, saccharose, or glycerin but acid was 

 formed in percentages varying from SO to 21 per cent of the forms with the 

 different sugars. Nitrates were reduced l)y 59 per cent of the forms and starch 

 was attacked by 20 per cent. The Gram stain was positive with 96 per cent." 



Stud,ies of long staffs forms of lactic acid bacteria (lactobacilli), C. Bab- 

 THEL {K. Landtlr. Akad. Hand], och Tidskr., 51 (1912), No. 7-8, pp. 559-5S3; 

 Meddel. Centralanst. Forsoksv. Jordhruksomradet, 1912, No. 68, pp. 27, pis. 2, 

 figs. 9). — Studies are described of the bacterial flora of different cultures of 

 yoghourt, of samples of milk, and of 2 pure cultures of Bacterium casei obtained 

 from von Freudenreich and Burri. in 1903 and 1911, respectively. 



Some factors affecting the bacteriological content of milk, A. Lauder and 

 A. Cunningham {Edinh. and East of Scot. Col. Agr. Rpt. 28, 1913, pp. 17, 

 pis. 3). — This is a report of experiments to determine the various factors which 

 influence the bacterial content of milk. The milk was carefully drawn to 

 preclude infection by outside agencies, " samples taken in sterile glass bottles 

 by means of sterile copper dippers, and as a rule the determinations were com- 

 menced immediately." The diluted sample was mixed with sterile agar medium, 

 poured into a sterile Petri dish, and incubated at 22° C. for 72 hours. 



The bacterial content of the milk was materially lessened by grooming and 

 washing the udder. In another test it was determined that feeding and 

 grooming cows, or the removal of manure from the barn during the time of 

 milldng, greatly increased the bacterial content of the air and hence that of 

 the milk. Immediate cooling of milk to the tempei-ature of the air greatly 

 retarded bacterial growth. In an effort to set a bacteriological standard for 

 clean milk 53 samples from the herd at Bangour were examined and showed 

 an average bacterial content of 47,906 bacteria per cubic centimeter of milk. 

 Orr has previously suggested that clean milk, as it leaves the barn, should not 

 contain more than 50,000 bacteria per cubic centimeter. 



