Having- ascertained the fact that numerous g^as-producing bacteria 

 were present in the milk as deUvered at the factory, the next step was lo 

 try to find out how the gas-producing organisms got into the milk. 



Some investigators have shown that the milk before it leaves the 

 udder may be contaminated with bacteria, and further that these bacteria 

 were occasionally gas-producing organisms. There is also a well known 

 fact that inflammation of the udder (mastitis) is, at times, caused by gas- 

 producing bacteria. Taking every possible precaution to guard against 

 the entrance of germs from the air, and from the hairy coat of the animal, 

 we examined the milk from the 25 cows comprising the Dairy herd, and 

 from the milk of two of them a number of gas-producing bacteria were 

 isolated. The results of this experiment are important, because it ex- 

 plains why some of the factory inspectors, have been able to trace gas pro- 

 duction to a single cow in a herd. 



Photograph of gelatin jjlate, made from a 

 drop of milk, shewing colonies of gas-produc- 

 ing germs. Each white dot is called a 

 colony, and is made up of huge numbers of 

 individual germs, the result of the continued 

 growth of a single germ that was in the drop of 

 milk, and which was held in place when the 

 gelatin solidified. Note the gas bubbles at G. 



Thirteen analyses were made of the stable air, but this was remark- 

 ably pure and no gas-producing bacteria were found. 



During the movements of milking, particles of skin, hair, etc., and 

 with them bacteria, are dislodged from the animal's coat, and drop into 

 the milk pail. We found that gas-producing bacteria were present upon 

 the hairv coat of the animal. When the udder and flanks were wiped 



[3] 



