288 



Society Proceedings (122). 



to prevent the escape of C0 2 , the fluid was not allowed to come 

 into contact with the air. 



Results. — The reactions of 16 joint exudates from patients with 

 acute rheumatic fever were all slightly alkaline; their hydrogen- 

 ion concentration varied from P H 7.2 to 7.38. Seven exudates 

 from patients with chronic arthritis varied in P H from 7.27 to 7.4. 

 An exudate aspirated from a knee infected with Staphylococcus 

 aureus had a P H of 6.63 and that from a knee infected with Strepto- 

 coccus hcemolyticus -was also acid, having a P H of 6.14. 



Since a definitely acid medium is necessary for the liberation 

 of salicylic acid, and since all of the joint exudates from acute 

 rheumatic fever patients were slightly alkaline, no free salicylic 

 acid can exist in these joint fluids following the administration 

 of salicylates. 



127 (1874) 



The selective bactericidal effect of acid fuchsin and 

 sodium chloride. 



By JOHN W. CHURCHMAN. 



[From the Department of Hygiene, Cornell University Medical School, 



New York City.] 



In 1912 it was found that if bacteria be stained with gentian 

 violet and planted on plain agar a sharp selective activity of the 

 dye could be readily demonstrated. All the commoner gram- 

 negative organisms survived even long exposure to the stain, 

 while all the commoner gram-positive spore-bearing aerobes were 

 "killed," even by a relatively short exposure. Even the spores — 

 though not deeply, if at all, stained by gentian violet — were 

 "killed" by exposure to the dye. What was true of gentian 

 violet was found to be true also of other basic dyes of the tri- 

 phenyl-methane group. 



It is now found that a cleavage in exactly the opposite sense 

 occurs if organisms be exposed to acid fuchsin — an acid dye of the 

 tri-phenyl-methane series. Whereas gentian violet kills the 

 gram-positive spore-bearing aerobes and spares the commoner 

 gram-negative bacteria, acid fuchsin spares the former and kills 



