10 WOUND TREATMENT 



of disinfectants is responsible for most of the discrep- 

 ancies in results obtained by different workers with 

 the same disinfectant. Close attention to the details of 

 the method used is the only way in which uniform results 

 can be secured. 



The factors which bring about the greatest variance 

 in results obtained, and which must be considered of 

 the most importance in the conduct of the test, are (1) 

 the organism used, (2) temperature of the experiment, 

 (3) amount of culture, (4) amount of disinfectant, and 

 (5) the media used in subculture, (6) standardized 

 solution of phenol. 



The coefficient obtained by different species, and by 

 different strains of same species, may vary greatly, so 

 it is essential that one species be adopted and the cul- 

 tivation of the strain employed be as nearly standard- 

 ized as possible. For this reason the Hopkins strain of 

 B. typhosus is best employed. It is cultivated on stand- 

 ard extract broth made from Liebig's extract of beef 

 in accordance with the methods adopted by the Amer- 

 ican Public Health Association for water analysis. It is 

 important that the reaction of the medium be just 11.5. 

 One loopful of 4-millimeter platinum loop of the cul- 

 ture is carried over every twenty-four hours on three 

 successive days. Before being added to the disinfectant 

 the culture is filtered through sterile filter paper and 

 brought to a temperature of 20 degrees Centigrade in 

 a water bath. 



One tenth of a cubic centimeter of the culture is used, 

 added to 5 cubic centimeters of the disinfectant dilution 

 at a temperature of 20 degrees Centigrade. Measure 

 the amount of culture with a pipette graduated to 1-10 

 cubic centimeter. 



When the proper dilutions of the disinfectant to be 

 tested and the phenol controls have been made and 



