1 88 BACTERIA 



Royal Society of Edinburgh. He estimated that in the 

 Edinburgh milk supply three hours after milking there 

 were 24,000 micro-organisms per cc. in winter ; 44,000 in 

 spring ; 173,000 in late summer and autumn. Again, he 

 found that five hours after milking there were 41,000 micro- 

 organisms per cc. in country milk, and more than 350,000 

 micro-organisms per cc. in town milk. Many London milks 

 would exceed 500,000 per cc. 1 



There is no standard or uniformity in the numerical esti- 

 mation of bacteria in milk. A host of observers have re- 

 corded widely varying returns due to the widely varying 

 circumstances under which the milk has been collected, 

 removed, stored, and examined. Nor is it possible to es- 

 tablish any standard which may be accepted as a normal 

 or healthy number of bacteria, as is done in water examin- 

 ation. Bitter has suggested 50,000 micro-organisms per cc. 

 as a maximum limit for milk intended for human consump- 

 tion. 



But owing to differences of nomenclature and classification, 

 in addition to differences in mode of examination at present 

 existing in various countries, it is impossible to state even 

 approximately how many bacteria and how many species of 

 bacteria have been isolated from milk. Until some com- 

 mon international standard is established mathematical 

 computations are practically worthless. They are needlessly 

 alarming and sensational. And it should be remembered 

 that great reliance cannot be placed upon these numerical 

 estimations. They vary from day to day, and even hour to 

 hour. Furthermore, vast numbers of bacteria are economic 

 in the best sense of the term, and the bacteria of milk are 

 chiefly those of a fermentative kind, and not disease- 

 producers. 



Kinds of Bacteria in Milk. It is clear from the foregoing 

 that the only valuable estimation of bacteria in milk is a 



1 British Medical Journal, 1895, vol. ii., p. 322. 



