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. 179 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 



