1 94 BACTERIOLOG Y. 



manent, and there is never any danger of its presence 

 being masked by the occurrence of other color reactions. 

 Test for Nitrites. For this purpose Lunkewicz has 

 recently recommended the employment of Ilosvay's 

 modification of the method of Griess. As reagents the 

 following solutions are employed : 



a. Naphthylamine 0.1 gramme. 



Dist. water 20.0 c.c. 



Acetic acid (25 per cent, sol.) . . . 150.0 c.c. 



6. Sulfanilic acid . . . . . . 0.5 gramme. 



Acetic acid (25 per cent, sol.) . . . 150.0 c.c. 



In preparing solution a the naphthylamiue is dis- 

 solved in 20 c.c. of boiling water, filtered, allowed to 

 cool, and mixed with the dilute acetic acid. 



Solutions a and b are then mixed. The resulting 

 mixture should be colorless. It is best to prepare it 

 fresh as it is needed, though if kept in a closely stop- 

 pered flask it retains its virtues for some time. 



When added to cultures containing nitrites, in the 

 proportion of one volume to five volumes of the culture, 

 a deep red color appears in a few seconds. If nitrites 

 are not present no color reaction occurs. In making 

 the test on cultures always control the results by tests 

 on the same medium not inoculated, as some of the in- 

 gredients of which the medium is composed may con- 

 tain nitrites. Lunkewicz recommends the use of Merck's 

 peptone for this test, claiming that nitrites are always 

 to be found in Witte's peptones. 



POINTS TO BE OBSERVED IN DESCRIBING AN ORGANISM. 



The following is an outline of points to be considered 

 in describing a new organism or in identifying an or* 

 ganism with one already described ; 



