Effect of External Influences. 



taste, in the same manner as is the case with the prolonged action 

 of ultra-violet rays. 



It is important during transportation that the vessels be 

 closed in an air tight manner, and with a cover consisting of 

 non-porous material. 



All milk utensils should be cleaned with hot soda solution, 

 with subsequent rinsing in fresh pure water, and if possible com- 

 bined with steam sterilization and rapid drying in places protected 

 from dust. 



The transportation of milk should be rapid, and where pos- 

 sible it should be shipped after each milking. 



In creameries the treatment of milk after its receipt should 

 be principally confined to cooling. This cooling is carried out in 

 deep cooling appliances or double coolers in which the abstraction 

 of the heat takes place through water at the point at which the 

 milk flows into the cooler, and the lower part is further cooled 

 with ice water or with brine. All further manipulation and at- 

 tempted improvements of milk for drinking purposes are of no 

 use. Spoiled milk should be excluded from the market and not be 

 subjected to renovating processes. 



Thus in some creameries it is customary to clean the milk not 

 only by renewed filtration, but also by centrifugalization, which is 

 frequently done on the supposition that the bacterial content of 

 milk becomes reduced through such treatment. This, however, is 

 impossible ; on the contrary, such milk often becomes contaminated 

 again by bacteria from the non-sterilized centrifuges, and even if 

 the milk is centrifuged in a sterilized apparatus only those bacteria 

 will be eliminated which adhere to the courser bodies having a 

 higher specific gravity (pus, fibrin, filth, casein coagulum, etc.). 



The separator slime therefore contains principally fodder and 

 manure bacteria, lactic acid bacteria, species of milk moulds, and 

 bacteria of those fermentation processes which take place in the 

 residue of milk cans and transportation vessels, and further the 

 specific causative agent of mastitis occurring in pus. 



Therefore, although a great number of bacteria are removed, 

 the bacterial count through plating of the centrifuged milk dis- 

 closes a considerably larger number of bacterial colonies than 

 was the case in the milk prior to centrifulgalization, although the 

 short time of the centrifuging process does not permit of an 

 actual increase of the bacteria. Severin observed an apparent 

 increase in bacteria up to 70%. This may be explained by the 

 fact that through centrifugalization, bacterial clumps and colonies 

 floating in the milk, and the clumps of pus and fatty leucocytes 

 which have embodied bacteria, are broken apart, and the bacteria 

 are thereby distributed in the milk. Therefore, in spite of the 

 removal of considerable numbers, there is an apparent increase. 

 This distribution is such that the separator slime and cream 

 are considerably richer in bacteria than the skim milk. The 



