MUNICIPAL HYGIENE 711 



of their clothing, hands, and occupation, are called upon 

 to assist in milking the cows, and the remarkable thing is 

 that more trouble does not arise from this practice than 

 we hear of. Medical Officers of Health will do well to 

 carefully examine into this serious source of contamination 

 before blaming the cow. 



There are several fermentations known to occur in milk 

 outside the body, some of which are destructive of the 

 fluid, while others are turned to useful advantage in the 

 dairy. 



There are over one hundred different kinds of lactic acid 

 organism known ; the lactic acid is produced by the action 

 of the bacterium on the sugar of milk. The most favour- 

 able temperature for its production is 60° P., which is the 

 explanation why milk should be cooled on withdrawal from 

 the body, for the more rapidly it is cooled the longer it 

 will keep. 



The lactic acid organism can also be destroyed by raising 

 the temperature of the milk to 158° P., so that two opposite 

 conditions effect the same result, so far as the organism is 

 concerned, viz., cooling or heating. 



Lactic acid fermentation is capable, so it is said, of 

 liberating, under certain conditions, some very poisonous 

 products from the casein of milk, which have played an 

 important part in ice-cream poisoning of man. 



The butyric bacillus is concerned in butyric fermentation, 

 which breaks down both the casein and milk sugar. 



The viscidity of some milk, which is frequently a patho- 

 logical condition, may also occur after the milk has been 

 drawn from the body, and is due to several organisms of 

 which eighteen varieties are known to exist. It is also well 

 to remember that special kinds of food may produce the 

 same condition, such as tares and ' butter- wort ' ; the latter 

 is in Norway purposely introduced into the milk, in order 

 to produce a ropy condition which is much appreciated. 



When viscidity occurs in milk on standing, it is practically 

 always due to infection from without, dirt in the vessels or 

 dairy, and not due to the cow. 



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