256 MODERN DAIRY PRACTICE. 



center, and the gray color will gradually disappear, until it 

 is entirely gone. This bacteria will therefore hardly be 

 able to spoil larger quantities of butter. Neither is there 

 any difficulty in keeping it away from the milk, it being 

 unable to stand even a heating to 130 F. 



8. Blue Butter. This disease has so far only been 

 found in Central Europe. It appears in butter made 

 from the abnormal milk called bluish milk, and is caused by 

 a bacterium (Bacillus cyano genus).* The Germans Haub- 

 ner and Fiirstenberg and the Frenchman Reiset state that 

 they have frequently met with such blue butter. Haubner 

 says, however, that if the butter was well prepared and 

 carefully washed the blue milk would not produce dis- 

 eased butter, but only in case of a greater quantity of but- 

 termilk remaining in the butter. I have also been in 

 position to investigate this subject and have corroborated 

 Haubner's results. 



9. Moldy Butter. Butter may assume a moldy taste 

 and flavor also in other cases than when very old. I have 

 found it in rather fresh butter which had small white 

 specks both on its surface and in the inner portion of the 

 mass. By microscopic examination the specks proved to 

 be mold-fimgi. The fungus did not grow on any of the nu- 

 tritive substances on hand at that time, so it could not be 

 further studied. Segelcke met with moldy, green-colored 

 butter in 1879. 



It may be clear from the preceding accounts of the 

 main studies and investigations at hand concerning the 

 production and keeping of milk and other dairy products 



* See, further, " Saprophytic Micro-organisms in Cow's Milk," p. 63. 



