50 



CREAMURV BUTTER MAKING 



these is blue. It is, however, not often met with in dairy 

 practice since the color usually does not appear until the 

 milk is several days old. The specific organism that 

 causes blue milk has been known for more than half a 

 centurv and is called cyanogenous. Another color that 

 rarely turns up in dairy practice is produced by a germ 

 known as prodigiosis, causing milk to turn red. Other 

 colors are produced such as yellow, green, and black, but 

 these are of very rare occurrence. 



Fig. 15. — Composite 

 test jar. 



