MICRO-ORGANISMS IN MILK 273 



smaller in proportion would be the germ content. One fact, 

 however, is established by the work accomplished so far, and that 

 is the constancy with which bacteria are present in all parts of 

 the udder, except possibly only in the secreting glands. 



Some figures are available to show whether bacteria multiply 

 in the udder. Stocking has found that when the udder is not 

 milked dry the milk from the next milking contains a greater 

 number of bacteria than when the udder is milked dry. In a 

 series of experiments bearing upon this point he found that when 

 the udder was milked dry the germ content of the product of the 

 next milking was 6542 bacteria per cubic centimeter against 11,- 

 324, when the udder was not milked dry. Lux approached the 

 subject from another direction. He milked the udder dry and 

 then commenced taking samples two hours later at regular in- 

 tervals, and determined the bacterial content, with the following 

 results: 



BACTERIAL CONTENT OF MILK LEFT IN THE UDDER 



After Right front quarter. Left front quarter. 



2 hours 22 65 



4 



365 221 



400 230 



112 217 



897 K97 



1217 2933 



The experiments of both Lux and Stocking show clearly that 

 there is a limited degree of multiplication in the udder, and milk- 

 ing the udder dry is advantageous from this point of view. 



The distribution of bacteria in the milk while in the udder 

 appears to be subject to considerable variability. It seems es- 

 tablished, however, that the first streams always contain more 

 germs than later milking, but how many streams must be dis- 

 charged before the number approaches the average germ con- 

 tent of the mixed milk has not been thoroughly investigated. It 

 is thought that by discarding the first few streams the bacterial 

 content of the whole product can be materially lowered. Experi- 

 ments made by Stocking throw some light on this question. By 

 determining the bacterial content of the first fourteen streams and 

 comparing this with the number of bacteria in the strippings 

 Stocking found the following figures: The first two streams in 

 four experiments averaged 10,143 bacteria per cubic centimeter; 

 streams five and six averaged 2347; streams nine and ten, 272; 

 streams thirteen and fourteen, 382; and the strippings, 204. To 

 judge by these figures the first six streams discharge the greatest 

 number of bacteria and later milk contains materially smaller 

 numbers. 



However, the quantity of milk represented by the first six 

 streams is small as compared with the whole product, and when the 



18 



