BACTERIAL PROTEINS 37 



ble in absolute alcohol. However this substance 

 gives the biuret test and this is generally re- 

 garded as the most distinctive test for proteins. 

 Its alcoholic solutions are precipitated by alco- 

 holic solutions of copper, mercury and plati- 

 num. By means of these precipitants with sub- 

 sequent removal of the metal with hydrogen 

 sulphide, we have obtained our most potent 

 preparations. By this method we have ob- 

 tained a body which kills guinea-pigs of from 

 two hundred to three hundred grams weight in 

 doses of 0.5 mg. given intravenously. The 

 poison is not an alkaloid, although it may be 

 basic in character. 



ACTION ON ANIMALS. The comparative ef- 

 fects of the living bacillus, the dead cellular 

 substance and the crude soluble poison on ani- 

 mals was first worked out by V. C. Vaughan, 

 Jr. The organism used was the colon bacillus. 



(a) The Living Bacillus. When a guinea- 

 pig receives a fatal dose of the living colon 

 bacillus intraperitoneally there is a period of 

 from five to twelve hours, varying with the size 

 of the inoculation, during which there are no 

 recognizable symptoms. We regard this as the 

 period of incubation, and it is roughly propor- 

 tional to the amount of the culture used and to 

 some extent to the virulence of the organism or 



