Principles of Milk Preservation. 



99 



The fresher and better the milk, the less likely it is to 

 contain deleterious spore-bearing bacteria which are not 

 destroyed by pasteurizing. The unhindered development 

 of these germs in the milk may sometimes give rise to the 

 production of decomposition products that are toxic or 

 at least highly irritating in their character 1 . 



FIG. 17. Relative consistency of pasteurized cream, before (.A) and after (B 

 treatment with viscogen. Cream flowing down inclined glass plate. 



1 00. Selection of milk. Milk for pasteurizing should 

 be as clean as possible, for in general terms, the bacteria 

 associated with filth and dirt, more especially manure 

 particles, belong to the spore-bearing putrefactive class. 



1 Flugge, Zeit. f. Hyg., 17: 272. 



