94 BACTERIA IN MILK 



as high as 15,000 per c.cm. have been obtained, it is probable 

 that at least a portion of this number was due to external con- 

 tamination caused by faulty aseptic conditions of milk with- 

 drawal. 



Sedgwick and Batchelder* found that with moderate pre- 

 cautions on the part of the milker, the organisms in fresh milk 

 may not exceed 500 to 1000 per c.cm., but if ordinary flaring 

 pails were used with more or less disturbance of the bedding 

 and shaking of the udder, the count may be 30,000 or even more. 



Park 5 found the average count from six separate cows, 

 five hours after collection, to be 4000 per c.cm. (minimum 400 

 per c.cm.) and the average of 25 cows as 4550. 



McConkey ^ observed that, with ordinary care and cleanli- 

 ness, it was possible to obtain milk containing less th^n 1500 

 bacteria per c.cm. and that such milk should not contain gas 

 formers in less than 50 c.cms. 



Von Freudenreich "^ thought it would be easy to obtain 

 sterile milk by using strict asepsis but soon found otherwise. 

 Such milk invariably contained 250-300 bacteria per c.cm. 

 though the hands of the milkers and the teats of the cows were 

 washed with soft soap and sterile water, then with servatol soap 

 and sterile water, and, finally with sterile water and then dried 

 on a sterile towel. The milkers' hands were smeared with lano- 

 line and the fore milk rejected. The bacterial content of the 

 mixed milk of 28 cows so milked varied from 65-680 per c.cm. 

 Von Freudenreich and Thoni ^ from a further series of experi- 

 ments concluded that freshly drawn milk, even when every 

 precaution is taken against contamination, always contains 

 bacteria; they found that these were mostly cocci and were 

 derived from the udder. A' summary of the more important 

 attempts to obtain sterile milk is as follows: 



