262 BACTERIOLOGICAL ANALYSIS OF MILK. 



to 10,000, and very frequently there will be more than this ; 

 50,000, 100,000 bacteria per cubic centimeter, or even larger 

 numbers, may be found in the milk freshly taken from dairies 

 where the conditions are bad. The examination of market 

 milk as it is distributed to the consumer shows far wider 

 variations. In small communities where the dairy is close 

 to the consumer, the number present in the milk, as distrib- 

 uted, may be no more than 10,000 per c.c. or occasionally 

 even less; though even in such small communities the 

 number may rise to several millions per c.c. In the market 

 milk of large cities the number is more variable and is 

 usually higher, since the distance from the farm to the con- 

 sumer may be great. In the larger cities of America the 

 number of bacteria found by analysis ranges all the way from 

 10,000 per c.c., in cases of exceptionally good milk, to many 

 millions; 20,000,000 per c.c. being frequently found in 

 samples of milk in summer weather, and occasionally even 

 this number is surpassed. Some samples of city milk have a 

 bacterial content of over 100,000,000 per c.c., although such 

 extremely high numbers as this are unusual and indicative of 

 some exceptionally bad conditions. The average number in 

 milk of large cities in the winter season may generally be 

 reckoned by tens or hundreds of thousands, while in summer 

 weather the number must commonly be reckoned by mil- 

 lions. The milk furnished by different dealers varies so 

 widely that an average number for the city gives no guide as 

 to the number to be found in any sample. 



Interpretation of these Results. -^-The interpretation of 

 these results is certainly not what would at first be expected. 

 It is evident that the problems of bacteria in milk and in 

 water are quite incomparable. Whereas a sample of water 

 which contains a few thousand bacteria per c.c. is justly re- 

 garded as suspicious, many a sample of milk contains bacteria 

 by the hundreds of thousands, and possibly by millions, and 

 yet is perfectly wholesome. Even when compared with sew- 



