30 THE UNIVERSITY SCIENCE BULLETIN. 



Several samples of butter were also examined for the butter ba- 

 cillus. 



The pui'e cultures were carried along on glycerine agar, plain 

 agar, and in glycerine broth. Cultures varying from one to three 

 weeks in age were found satisfactory. 



In studying the relative efficiency of Gabbet's, Pappenheim 's, 

 acid-alcohol, etc., as decolorizing agents the standard was the 

 number of acid-fast organisms present when decolorized with 3 

 per cent nitric acid in water. Several slides were run on each of 

 these as controls and in making estimates. 



In the following table four plus (H — \ — h +) indicates com- 

 plete acid -fastness with the reagent used, while a minus sign ( — ) 

 indicates non-acid-fastness. The intermediate degrees are indi- 

 cated by the number of plus signs, varying between the two 

 limits. Where only a few organisms retain the stain, and that 

 only to a slight degree, the double dagger is used (if). 



