256 BACTERIA IN MILK AND THEIR SOURCES 



stations in London : Orr's figures for similar samples 

 at several Yorkshire stations were 19,800 to 3,620,000, 

 with an average of 232,600 per c.c. 



At present milk is sold in all sorts of shops, some 

 of them clean, but the majority unsatisfactory from the 

 point of view of a clean milk supply. The vessels in 

 which the milk is stored is, in many instances, open to 

 the visits of flies and to the access of dust blown in from 

 the street, the measures are not always clean, and, where 

 the milk is stored in the living room of a house, there is 

 considerable risk of infection with pathogenic organisms. 



The estimation of the amount of contamination which 

 takes place after the milk has left the farm, and due to 

 the several causes enumerated, cannot be accurately 

 made on account of the increase brought about by the 

 growth and multiplication of organisms during transit to 

 the consumer, this disturbing influence being especially 

 active in summer, when the temperature is comparatively 

 high. 



According to Swithinbank and Newman's investiga- 

 tions, the milk retailed in London usually contains from 

 340,000 to nearly 5 millions per c.c. ; in New York, 

 Park found from I to 5 millions per c.c. 



In the private houses of the consumer additions are 

 made to the bacterial content, the amount varying with 

 the place of storage, the cleanliness of the receptacles 

 in which the milk is kept, and other factors. 



Orr concluded from his investigations in Yorkshire 

 that the farmer was responsible for about 40 per cent, 

 of the organisms present in the consumer's milk, the rest, 

 or 60 per cent., being contributed in approximately equal 

 amounts by the dairyman, the consumer himself, and by 

 pollution during the railway journey. 



