THE MILK CONTRACTOR 283 



must be admitted but practically they have not proved serious obstacles 

 to the success of the process. Galloway tells that in a plant in Portland, 

 Ore., which was pasteurizing milk by the holder method at 140F., the 

 milk entering the pasteurizer showed a bacterial count of 50,000 per 

 cubic centimeter and that issuing from it 200,000. Investigation showed 

 that the inside of the pipes were so badly corroded and pitted that the 

 machine could not be kept clean. In a Milk Plant Letter of the U. S. 

 Department of Agriculture it is stated that the pasteurizer is one of 

 the most difficult pieces of machinery to keep clean but that it must be 

 kept so, for if it is not, on the inside a cooked layer forms which daily 

 grows worse. The self-interest of the contractor operates to keep down 

 this sort of thing for it is likely to make itself known to customers in a 

 product so inferior that they reject it. The watchful eye of an alert in- 

 spector is a good corrective to uncleanliness. Epidemics have seldom 

 been traced to pasteurized milk and of the few that have, only a small 

 percentage were thought to be derived from the men who were doing 

 the pasteurizing. 



Milk Liable to Recontamination after Pasteurization. Except when 

 the pasteurization is done in the bottle there is opportunity for the milk 

 to be re' contaminated in the bottling and capping. In fact before it had 

 been ascertained that lactic acid bacteria survive pasteurization at low 

 temperatures, several observers were inclined to attribute the souring of 

 commercially pasteurized milk to this recontamination, and brought forth 

 the suggestion that instead of depending on this chance method to bring 

 about the desirable souring of pasteurized milk it would be well to assure 

 it by inoculating the pasteurized milk with a lactic culture. This pro- 

 cedure was never practised. No doubt some contamination with lactic 

 and other germs does occur after the milk is pasteurized, and this being 

 the case it must be admitted that there is an opportunity also, for the 

 pasteurized milk to be infected either by the men who bottle and cap it, 

 provided any of them are sick with, or are carriers of, infectious disease, 

 or by filling the milk into insterile infected bottles and other containers. 

 Bottle infection of pasteurized milk was suspected to have actually 

 occurred in Rockford, 111., in 1913. The infection of milk subsequent 

 to pasteurization and before delivery to the consumer is very unusual 

 but it may occur, and both health officers and the public should know 

 that while the chances of pasteurized milk becoming a medium for the 

 spread of communicable disease are remote, they nevertheless exist. 

 So long as it was believed that germs grew more rapidly in pasteurized 

 than in raw milk, there was considerable concern over dangers that it 

 was conceived might arise from the contamination of pasteurized milk 

 in the home of the consumer, but anxiety on this score has dissipated. 



Overconfidence in Pasteurized Milk. The last objection to the use 

 of pasteurized milk that merits notice is the contention that pasteuriza- 



