Reduction of Bacterial Content. 155 



in the milk from animals free from udder affections, and which 

 has been drawn under aseptic conditions, the groups of staphy- 

 lococci, colon bacteria, Bacillus subtilis and B. mesentencus should 

 be especially mentioned. Seibold also demonstrated acid-fast 

 rods. Eullmann and Trommsdorff found no representative of the 

 colon group, but they isolated staphylococci, a few representa- 

 tives of spore-bearing species, and especially the anthracoides 

 (mycoides) species. 



In ordinary milk production there also come into consider- 

 ation an army of air and stable bacteria, which adhere to the 

 food, manure and litter, as well as those which vegetate, as 

 saprophytes, on the skin of cattle, especially on the skin of the 

 teats, and on the hands of the milker, besides those groups of 

 bacteria which colonize with special predilection on milking 

 utensils and in the cans. 



The number and kind of bacteria found by the different 

 authors vary to a considerable extent, depending upon the degree 

 of cleanliness used in obtaining the several samples. 



Dean found in milk 



From filthy cows 9,845 to 17,155 bacteria per c. c. 



From clean dry cows 8,295 to 9,426 bacteria per c. c. 



From cows with dampened skins 640 to 2,350 bacteria per c. c. 



The same work also throws light on the influence of the milk 

 vessels. If the milk was collected in sterile milk vessels, 



it contained 355 to 1,702 bacteria per c. c. 



In well cleansed milk vessels. 13,080 to 93,420 bacteria per c. c. 

 In dirty milk cans 215,400 to 806,320 bacteria per c. c. 



Russell, in using sterile milk vessels, found 165 bacteria per 

 c. c. in freshly drawn milk, while in case of only ordinary cleansing 

 there were 4,625 bacteria per c. c. in such freshly procured milk. 

 Grotenfeld counted in the milk from well-kept animals, in clean 

 stables, only 106 bacteria as compared with 670,000 per c. c. in 

 milk from dirty stables. 



The kind of milk can also has an influence. Backhaus con- 

 siders enamel cans as the best; tin vessels were found to be 

 almost as good, while milk vessels constructed of wood were 

 unsatisfactory. 



The work of Koning shows the influence of the bacterial flora 

 of the air on the bacterial content of the milk. The author counted 

 500,000 to 700,000 bacteria in the stable air, whereas the outside 

 air contained only 90,000 bacteria. He found that the volume of 

 air between the cows was especially rich in bacteria. Milk which 

 is procured in the pasture contains fewer bacteria than stable 

 milk. If it is customary to change the straw and also feed shortly 

 before or during the milking time, these factors tend greatly to 

 increase the bacterial content of the milk. 



If the milk is subjected to the so-called " improving methods" 

 of the most varied kinds, and has to be transported for long dis- 



