GERMICIDES AND ANTISEPTICS. - 211 



the motile bacteria a test of germicide power. 

 But it is evident that this is unreliable, and the 

 only safe test is failure to multiply, under favora- 

 ble conditions, in a suitable culture-fluid. This 

 test requires care in its application, as contamina- 

 tion of the culture-fluid by other organisms than 

 those which have been subjected to the action of 

 the germicide agent would give a misleading 

 result. 



The method adopted by the writer in a series of 

 experiments, the results of which are published in 

 the " American Journal of the Medical Sciences," 

 April, 1883, is very satisfactory and reliable. This 

 consists in the use of the little culture-flasks, con- 

 taining a sterilized organic infusion, prepared as 

 directed on p. 176 of the present volume. 



The bacteria which serve as a test are subjected 

 to the action of the germicide in a small glass 

 tube, previously sterilized by heat; and, after a 

 given time, which in the experiments referred to 

 was two hours, the fluid in the culture-flask is in- 

 oculated with a minute drop of fluid from the tube 

 containing the test-organisms. The culture-flask 

 is then placed in the oven, at a temperature of 

 98- 100 Fahr. At the end of twenty-four to 

 forty-eight hours, inspection of the little flask will 

 show in a very definite manner whether the ger- 

 micide has been effectual or not : for the fluid 

 will remain unchanged and transparent if the test- 

 organisms were killed by the germicide agent ; or, 

 in case of failure, will have broken down, and will 



