H. WORMALD 225 



prepared in saturated solution in bouillon and the required dilutions 

 made with bouillon. 



In each of the two series of experiments four control tubes reserved 

 for comparison in the degrees of turbidity and sedimentation, were 

 prepared by adding 1 c.c. sterilized water to 9 c.c. bouillon in each 

 tube. Two of the tubes were inoculated, the other two left uninocu- 

 lated ; as the latter remained quite clear throughout the course of the 

 experiments thev were evidence that the method employed was satis- 

 factory for the preparation of such tubes free from outside contamination. 

 The tubes were kept at room temperature (18° — 19° C.) throughout the 

 experiment. 



Permanganate of Potash. This is unsuitable for experiments in 

 which bouillon is used, for with 0-1 % the permanganate settled in a 

 dense mass leaving a colourless liquid above in which motile rods were 

 to be found ; concentrations of 0-01 % and 0-001 % appeared to have 

 no inhibitory action whatever on the development of the organism. 



Copper Sulphate. A dense blue precipitate was formed on adding 

 to the bouillon a solution of copper sulphate sufficient to produce a 

 concentration of 0-2 % ; no growth however occurred. 0-1 % checked 

 growth and the medium remained clear for several days but it did 

 not wholly prevent development. At concentrations of 0-01 % and 

 0-001 % there was no evidence that growth was affected in any way. 



Mercuric Chloride. 0-01 % was sufficient to prevent development; 

 0-005 just failed to do so but had considerable retarding influence on 

 development, since the medium showed no signs of turbidity until after 

 the sixth day. Even with only 0-001 % no growth could be detected 

 until the third day. 



Carbolic Acid. 0-2 % sufficed to prevent growth while 0-1 % 

 caused retardation. 



Lysol. There was no growth with 1 % and very slight with 0-1 % ; 

 0-05 % retarded development but 0-01 % had no appreciable effect. 



Formaldehyde. In 0-01 % growth was inhibited completely ; 

 0-005 % and 0-001 % retarded development slightly. 



Chloroform. 10 % failed to prevent growth unless the tubes were 

 shaken, but 1 % sufficed to inhibit growth if agitated at frequent 

 intervals during the first six hours. 



Benzoic Acid. There was no growth in bouillon half saturated 

 with benzoic acid but development occurred when quarter saturated. 



Salicylic Acid. When at a concentration one-fifth saturated growth 

 was inhibited. 



