BACTERIOLOGY OF MILK 217 



the narrow part, and kept in place with glass-wool plugs 

 The volume of air having been aspirated through, the 

 sugar is pushed into the wide portion, a tube of melted 

 gelatin poured in, and after the sugar has dissolved a 

 roll-culture is made in the tube. 



Chattaway and Wharton's apparatus measures the air 

 driven through a glass tube by a rubber puff-ball bellows. 

 The air is met by a jet of nutrient medium automatically 

 sucked up by the current of air, as in a scent spray. 



The Bacteriology of Milk. 



Although the 'fore-milk' (the first portion drawn) 

 generally contains bacteria, which have obtained access to 

 the milk ducts since the previous milking, the milk in the 

 udder of a healthy cow is sterile. After leaving the cow , 

 excremental and other particles from the cowshed, the 

 hide, and the milker's hands, start a contamination which 

 does not cease to be augmented from extraneous sources 

 till the milk is consumed. Especially in poor neighbour- 

 hoods, flies are prominent factors in the pollution of milk. 

 Cox, Lewis and Glyn have shown that a housefly, while 

 drowning, may shed from 2,000 to 350,000 bacteria. 

 Flies are garbage feeders, and the bacteria carried in or 

 on their bodies are never desirable, and often pathogenic. 

 It is now proved beyond all doubt that flies can and do 

 infect milk with the organisms producing epidemic 

 diarrhoea of infants, typhoid, cholera, and dysentery. 



Milk is an admirable medium for the growth of bacteria , 

 and rapid multiplication takes place. Eyre states that 

 the numbers in London are about 3,000,000 to 5,000,000 

 in December, January, and February; and 20,000,000 to 

 30,000,000 in June to September. Milk may be the 

 medium by which the following diseases are conveyed 

 to man: Tuberculosis (pp. 62, 64), typhoid fever (p. 101), 

 sore throat (p. 134), diphtheria (p. 115), scarlatina (p. 195), 

 bacillary dysentery (p. 107), cholera (p. 154), Malta fever 

 (goat's milk, p. 145), foot-and-mouth disease (p. 199), and 

 infantile diarrhoea (p. 196). Milk is, in addition, subject 

 to various diseases peculiar to itself. 



Blue Milk. Blue patches are formed on the surface 

 by B. cyanogenus, a small motile multi-flagellate bacillus. 

 The organism does not liquefy gelatin, which, however, is 

 stained bluish-green, finally becoming of a dirty greyish 



