174 VICTOR BURKE 



of 10 minutes or more the slide was dipped in water to remove 

 free dye and lightly counter stained with aqueous Safranin O. 

 Upon examination the staphylococci were Gram negative and 

 the other two types of organisms weakly Gram positive. 



This experiment suggests that the dj^e-iodine precipitate in 

 solution in alcohol with the addition of alkali more readily 

 penetrates the Gram negative than the Gram positive organisms 

 used. The difference noted apparently is not due to a more 

 rapid decolorization of the staphylococci by the water. If the 

 films are examined after washing and before exposure to the 

 Safranin solution the three types of organisms appear to be 

 equally well stained. Since the counter stain more quickly 

 stains the staphylococci than the other two organisms we assume 

 that the staphylococci are less heavnly stained by the dj'^e-iodine 

 precipitate or are only surface stained rather than that the 

 Safranin has a greater affinity for the staphylococci. 



Staining by this method, as controlled at the present time is 

 entirelj'' inadequate from a practical point of view for distin- 

 guishing staphylococci from gonococci in mixed infections. The 

 results obtained are not uniform and the degree of differentiation 

 is not sufficient. 



EXPERIMENTS TO DETERMINE WHETHER THE PRIMARY STAIN 

 PENETRATES THE CELL WALL OF TYPHOID LIKE ORGANISMS 



Benians' conception of two types of Gram negative organisms 

 as described above is based upon two experiments as follows: 



1. If gonococci and Bacterium coli, unfixed by heat, are shaken 

 up in weak solution of methyl violet (1 to 40,000) and then 

 centrifuged, the gonococci are throwni douai well colored and the 

 dye is cleared out of the solution while the Bacteriuvi coli are thrown 

 down uncolored leaving the whole of the dye in solution. If the 

 Bacterium coli organisms were boiled or killed at 65° for thirty 

 minutes they absorbed the dye and were thrown down well 

 colored. The Bacterium coli organisms exposed to 60°C. for 

 thirty minutes did not absorb the dye. If the unfixed bacilli 

 were suspended in strong solutions they l^ecame deeply colored. 



2. When films of Bacterium coli organisms and Bacterium coli 



