248 AGRICULTURAL BACTERIOLOGY. 



cream it will not become rancid, but this same butter will de- 

 velop rancidity if it is mixed with a small amount of normal 

 butter. This proves that there is present in normal butter 

 something which is the cause of the rancidity and which is de- 

 stroyed by heat. It must be either enzymes or bacteria, but 

 which cannot yet be stated. No bacteria yet experimented 

 with will produce a rancidity in sterilized butter, a fact which 

 seems to point toward the presence of enzymes. On the other 

 hand, the presence of salt prevents the rancidity, and salt does 

 not have a checking action on enzymes, a fact which seems to 

 indicate the action of living bacteria. In short, the cause of 

 the rancidity of butter is still sub judice. 



From these facts it will be seen that the bacteria left in the 

 butter are of no considerable importance in determining the 

 subsequent changes. Most of them certainly die rapidly and 

 the few that are left have no special significance, unless it be 

 to contribute to the slow changes which develop in the butter 

 after long storing. 



BACTERIA IN OLEOMARGARINE PRODUCTS. 



This subject is closely related to the one just considered, 

 although possibly oleomargarine itself is to be regarded as an 

 industrial rather than an agricultural product. The materials 

 out of which it is made all come from the land. They consist 

 of stearin, lard, cottonseed oil and other oils. These are mixed 

 with the coloring matter annatto, warmed for thorough mixing, 

 and then the whole mass is drawn ofifinto cold water which chills 

 the oils into a hard mass resembling butter. The process is 

 certainly a useful method of utilizing quantities of oils which 

 would otherwise be waste products. It makes a wholesome, 

 digestible food, which could have no objection raised against 

 it if it could only be sold upon its own merits instead of under 

 the false guise of butter. So far as concerns the bacteria 

 normally present in oleo products, they are commonly much 



