22 Dairy Bacteriology. 



cheaper class of tinware now found on the market, the 

 soldering of joints and seams is very imperfect, anJ. this 

 affords a place of refuge for bacteria and dirt, as shown in 

 c, Fig. 6. 



Use of milk-cans for transporting factory by-products. 

 The general custom of using the milk-cans to carry back 

 to the farm the factory by-products (skim-milk or whey) 

 has much in it that is to be deprecated. These by-products 

 are generally rich in bacterial life, more especially where 

 the closest scrutiny is not given to the daily cleaning of 

 the vats and tanks. Too frequently the cans are not cleaned 

 immediately upon arrival at the farm, so that the condi- 

 tions are favorable for rapid fermentation. Many of the 

 taints that bother factories are directly traceable to such a 

 cause. A few dirty patrons will thus seriously infect the 

 whole supply. The responsibility for this defect should t 

 however, not be laid entirely upon the shoulders of the 

 producer. The factory operator should see that the refuse 

 material does not accumulate in the waste vats from day to 

 day and is not transformed into a more or less putrid mass. 

 A dirty whey tank is not an especially good object lesson 

 to the patron to keep his cans clean. 



It is possible that abnormal fermentations or even con- 

 tagious diseases may thus be disseminated. 



Suppose there appears in a dairy an infectious milk 

 trouble, such as bitter milk. This milk is taken to the 

 factory and passes unnoticed into the general milk-supply. 

 The skim-milk from the separator is of course infected 

 with the germ, and if conditions favor its growth, the 

 whole lot soon becomes tainted. If this waste product is 

 returned to the different patrons in the same cans that are 

 used for the fresh milk, the probabilities are strongly in 



