176 VICTOR BURKE 



Experiment 1. Films of Bacterium typhosum, Staphylococcus 

 aureris and Neisseria catarrhalis were air dried and stained over 

 night in a 0.5 per cent aqueous solution of methyl violet, then 

 exposed to the decolorizing action of water, weak alcohol, 100 

 per cent alcohol, acetone, and chloroform. In all cases the 

 typhoid organisms decolorized as rapidlj^ or more rapidly than 

 the other organisms. 



Experiment 2. The experiment was repeated with carbol- 

 fuchsin as the staining solution; similar results were obtained. 

 Increasing the period of exposure over the usual two minutes 

 period, increased the time required to bring about decolorization. 

 Apparently the increased exposure brought about a greater 

 concentration or greater penetration of the dye in the cell. There 

 is of course the possibility of a chemical change resulting from 

 the long exposure. 



Experiment 3. The above experiments were repeated but with 

 the appUcation of an iodine solution in the usual manner. The 

 typhoid and catarrhalis organisms decolorized at about the same 

 rate and much more rapidly than the staphylococci when exposed 

 to acetone. 



From these experiments we conclude that after the dye pene- 

 trates typhoid organisms the cell wall offers no greater resistance 

 to the removal of the dye than the cell wall of Neisseria catarrh- 

 alis and Staphylococcus. We have not demonstrated that the 

 dye penetrated the cells but since a similar exposure will result 

 in the staining of acid fast organisms we assume that the dye did 

 penetrate. The following experiments favor this assumption. 



Experiment 4- Films of Bacterium typhosum, Neisseria 

 catarrhalis and Staphylococcus aureus were air dried, stained for 

 two to three minutes in a 0.5 per cent aqueous solution of methyl 

 violet, washed in water to remove excess stain, stained lightly 

 with 2 per cent aqueous Safranin O, washed and cleared in xylol 

 for ten minutes. Upon examination the staphylococci almost 

 uniformly showed a safranin colored border with a dark center. 

 The safranin had penetrated part way into the cells and masked 

 the violet dye. The Neisseria catarrhalis organism resembled 

 the staphylococci with the exception that the Safranin had not 



