vi ] THE BACTERIA OF MILK 109 



however, that neither pasteurisation nor sterilisation 

 of milk impair to any extent at any rate its 

 digestibility. 



Importance of Cleanliness in Handling Milk. 



From what has been above said, it will be seen that 

 the sterilisation of milk is sometimes easily effected, 

 and sometimes with extreme difficulty. 



As illustrating the effect which even heating at a 

 comparatively low temperature has on the keeping 

 qualities of milk, it may be mentioned that Fleisch- 

 mann found by numerous experiments that milk 

 pasteurised at 70 to 75 C. (158 to 167 Fahr.), and 

 then maintained at a temperature of 12 to 14 C, 

 (54 to 57 Fahr.), kept at least thirty hours longer 

 than ordinary milk. If sterilisation is to be effectual, 

 it cannot be too strongly impressed upon the mind 

 of the dairyer that the greatest care should be taken 

 in handling the milk in as cleanly a manner as 

 possible. It is from the impurities which are apt 

 to enter into milk through dirty handling, such as 

 particles of manure, of skin, of food, hair, woollen 

 threads, cobwebs, etc., that the resistant spores 

 common to milk are derived. 



As exemplifying the influence of cleanliness, an 

 experiment carried out by the eminent German ex- 

 perimenter Soxhlet may be cited. A cow which 

 had been kept in a badly ventilated byre was milked 

 without having its udder previously cleansed. It 



