Effect of Organic Substances on Copper Sulphate 285 



Tenth-molar (fifth-normal) solutions of these salts were made up. 

 For use i c.c. of these solutions was diluted to 100 with ammonia-free 

 water. In the following tabulated results all referenees to the salt 

 solutions are to these dilute (N/500) solutions. 



The organic compounds. — Witte's peptone and Merck's "C. P." 

 dextrose were used. 



The typhoid cultures. — The culture used (Xo. 2006) was one of 

 those used in some earlier work. It was obtained from Dr. J. II. 

 Wright, of the Massachusetts General Hospital. It was taken from 

 the spleen at an autopsy on May 26, 1905. The clinical diagnosis 

 was typhoid fever. The culture, according to Wright, gave all the 

 ordinary tests for typhoid fever, including the Widal test. 



It was submitted to the ordinary diagnostic tests, with the follow- 

 ing results: fermentation tube with dextrose broth, growth in closed 

 arm, acid produced, no gas ; milk not coagulated, slight acid production ; 

 no indol from peptone; nitrates reduced slightly; gelatin not liquefied 

 in two weeks; growth on agar slant, scanty, thin, translucent; it 

 reacts with the sera of two rabbits into which two other strains of 

 typhoid organisms had been introduced subcutaneously. 



Cultures A, B, and C w^re obtained from plates made from 

 Bottle 2 in Experiment 5. They had lived for 48 hours in the 

 presence of a concentration of 0.63 parts of copper per million in 

 distilled water. They gave all the above tests exactly as the original 

 culture, except that they were not submitted to the Widal test. 



Technique 0} the experiments. — The experiments were made 

 under as uniform conditions as possible, and in the following manner: 



In all cases, except where tap water is specified, sterilized ammonia- 

 free water was used. When dextrose or other solutions were used, 

 these were made up with ammonia-free water and sterilized. The 

 organism was grown for 24 hours at 37° on the surface of an agar 

 slant. A loop of the culture was then removed and placcxl in 100 c.c. 

 of water. After thorough shaking, proper amounts of this suspension 

 were added to the bottles of water in which the experiments were to 

 to be made. These bottles were then thoroughly shaken, and the 

 the bacteria determined in each by properly diluting i c.c. and 

 plating. For plating agar was used, and all plates were grown for 1 5 

 hours at 37° C. The salt solution was then added. In the same manner 



