362 Bacteria in Relation to Country Life 



of bacteria. Fraser has shown that the weight of dirt 

 collected from under unwashed udders, while the milker 

 went through the motions of milking for four and one- 

 half minutes, was three and one-half times as great as 

 that collected under the same circumstances from 

 under the same udders that had been previously washed. 

 The 158 exposures under unwashed udders showed, 

 on the average, 578 colonies, while the same udders, 

 previously washed, led to the development of only about 

 a third of that number. 



These results are not at all surprising when we re- 

 member that a single gram of dirt collected on the cow's 

 body may contain as many as 80,000,000 germs. A 

 single hair may contain hundreds of thousands of bac- 

 teria and, not infrequently, much greater numbers. 

 Milk produced even in sanitary dairies is not always free 

 from appreciable quantities of dirt which collects as 

 sediment in the bottles. In the milk and cream contest 

 held in Cleveland, Ohio, in March, 1907, only about 

 one-third of the samples showed no sediment whatever. 

 Yet there is reason to think that more than ordinary care 

 was taken by the dairymen in the contest to produce 

 clean milk. A large proportion of the sediment in milk is 

 undoubtedly derived from the air; nevertheless, the body 

 of the cow and the hands and garments of the milker con- 

 tribute largely to it. This is particularly true of dairies 

 where the cows are not kept clean and where the milkers 

 pay scarcely any attention to personal cleanliness. 



A microscopical examination by Grotenfelt of the 

 dirt particles in unstrained, freshly drawn milk revealed 

 the presence of the fgllpwing substances: 



