366 PUBLIC HEALTH BACTERIOLOGY 



grm. ; in debating chamber 100,000 per grm. (B. coli 

 1000, streptococci 10, B. enteritidis sporogenes 1000) ; in 

 the division lobby 1,000,000 per grm. (containing 1000 of 

 each of.B. coli, streptococci, and B. enteritidis sporogenes) : 

 and in New Palace Yard, 100,000 per grm., of which 10,000 

 were B. coli, under 1000 streptococci, and 100 B. enteritidis 

 sporogenes). 



MILK. 



In a healthy cow the milk within the udder is sterile. 

 In the milk ducts and teats a certain number of bacteria 

 may be found, even in healthy animals. From the position 

 of the udder and the mode of milking, it is not possible 

 to collect milk under aseptic precautions, and in the 

 most favourable circumstances freshly taken milk in the 

 pail will yield 100 to 500 bacteria per c.c. Under ordinary 

 conditions the yield is much greater, varying from 2000 

 to 6000 per c.c where less care is used, and with careless 

 manipulation (the usual method), 30,000 to 100,000 per c.c. 

 With such a bacterial content from the beginning, it is not 

 surprising that at summer temperatures the count in 

 twenty-four hours should be enormous, reaching into 

 millions and even hundreds of millions per c.c. The 

 species found include almost all known varieties. 

 Swithinbank and Newman describe 120 " milk bacteria," 

 apart from organisms of water, soil, etc. The varieties 

 found are there largely because of their presence in the 

 environment, or their power to outgrow other species under 

 the cultural conditions. Pathogenic bacteria are found in 

 milk either (i) derived from the cow, e.g., tubercle 

 bacillus, actinomyces, anthrax bacilli, streptococci, foot and 

 mouth disease germ ; or (2) from the introduction into it 

 of infectious material of human origin, e.g., typhoid, diph- 

 theria, germ of scarlatina, cholera ; or (3) from the air, when 

 kept in unsuitable conditions. Under (2), the milking of 

 cows, or the handling of milk by persons suffering from 

 disease or by acute or chronic carriers of disease germs, 

 the use of infected water to rinse cans, and the pollution by 

 flies, are the main acting causes. The milk of infected 

 goats contains the germ of Malta fever. Besides these, 

 milk contains many faecal organisms derived from the 



