PRODUCTION OF MILK FREE FROM CONTAMINATION 281 



tion it will receive a fresh supply of micro-organisms, many of them 

 doubtless from the air, and a certain number will be added owing 

 to the difficulty of using strict cleanliness in every detail when 

 so many processes are involved. Moreover, it is almost impossible 

 for the temperature to be kept low throughout. 



In this country the transit of milk by bottles is extremely 

 expensive, and is in fact prohibitive for the general milk supply 

 at the present time. There are no means for keeping milk (sent 

 on a large scale) cool during transit, and there can be no doubt 

 that the temperature is often fairly high for a considerable period 

 before the milk reaches the dairy, especially when delivered to 

 large towns. 



Although it is not possible for all the precautions enumerated 

 above to be adopted for the general milk supply without raising 

 the cost of production to so high a figure as to be prohibitive for 

 the general population, much improvement in the bacterial content 

 of the general milk supply could be effected without any appreciable 

 increase in cost. For instance, the cleanliness of the milkers, and 

 in many respects of the cows and of the sheds in which the cows 

 are kept, would not entail any appreciable additional labour when 

 once the practice was started. The provision of satisfactory pails, 

 which have been shown to exercise a great effect upon the bacterial 

 content of the milk, is a very small item in the total cost of milk 

 production. Churns have been manufactured having an air 

 chamber round the milk, which aids very greatly in keeping the 

 milk at a low temperature during transit, if the milk has been 

 properly cooled before being put on the rail. These are perhaps 

 a somewhat expensive item, but doubtless could be supplied for 

 at least a part of the milk supplied by a number of farms even 

 where the total cost of production cannot be raised, and yet allow 

 a sufficient margin of profit to the farmer. 



A bacterial standard of 10,000 per c.c. is impracticable for the 

 general milk supply, but there is no doubt that a standard of some 

 tens of thousands only per c.c. could easily be attained if reasonable 

 precautions were taken. It is of course possible to kill the bacteria 

 by various methods, and it is advisable that all milk used should be 

 heated before use, but this in no way alters the need for obtaining a 

 reasonably low initial bacterial standard. So long, however, as the 

 public continues to be satisfied with a milk containing an immense 

 number of micro-organisms, so long, presumably, will the dairy 

 farmer continue his out-of-date and dirty methods. If the public 

 realised that the number of bacteria present in the average sample of 

 market milk is so great that, were the milk transparent, it would be 

 cloudy as the result of the presence of these organisms, more efforts 

 might be directed towards the production of a milk having a low 

 bacterial standard. The heating of milk, which kills this vast number 

 of organisms, does not remove the dead bodies of the bacteria which 

 have been present, nor does it destroy any harmful chemical sub- 



