248 



Value of Antiseptics 



A very simple and popular method of determining the 

 germicidal value is to make a series of dilutions of the re- 

 agent to be tested ; add to each a small quantity of a fresh 

 liquid culture, and at varying intervals of time transfer a 

 loopful to fresh culture media. By a little ingenuity this 



Same rod immersed in broth after exposure 

 to disinfectant. 



Fig. 72. Glass rod in test-tube, for use in testing disinfectants. 

 Tube 6 in. by f in. ; rod 9 in. by ^ in. Ring marked with diamond 1 in. 

 from lower end, to show upper limit of area on which the organisms 

 are dried. After exposure the rod is placed in a similar tube con- 

 taining broth, to test development, a, Cotton plug wrapped around 

 glass rod ; b, broth ; c, gummed label on handle of rod, for indenti- 

 fication; d, ring marked by diamond; e, dried organisms. 



method may be made to yield information as to both time 

 and strength. 



Hill * has suggested a convenient method of handling the 

 cultures, which are dried upon the ends of sterile glass rods 

 and can then be transferred from one solution to another or 

 otherwise manipulated (see Fig. 72). 



*" Public Health," vol. xxiv, p. 246. 



