90 BACTERIAL POISONS. 



soluble substances accompanying them by sedimentation and 

 decantation, washed the cells, dissolved them in a ().;"> per 

 cent, solution of potash by the aid of heat, precipitated the 

 albumin with dilute mineral acid, and, after repeated re- 

 solution in alkali and reprecipitation with acid, employed 

 the purified proteid in his experiments. Introduced with 

 antiseptic precautions under the skin, this substance invari- 

 ably causes suppuration. This demonstrates that the sub- 

 stance of the bacterial cell is not altogether inert. It is 

 impossible at present to say to what extent the course of 

 an infectious disease may be influenced by the breaking 

 down of a large number of bacterial cells and the intro- 

 duction of their substance into the blood. 



(6) The microorganisms may be intimately associated 

 with or may produce a soluble, chemical ferment, which, 

 by its action on the body, produces the symptoms of the 

 disease and death. This theory formerly had a number of 

 ardent supporters, among whom might be mentioned the 

 eminent scientist, DE BARY. But PASTEUR proved the 

 theory false when he filtered anthrax blood through earthen 

 cylinders, inoculated animals with the filtrate, and failed to 

 produce any effect. NENCKI made a similar demonstration 

 when he inoculated a two per cent, gelatin preparation 

 with the anthrax bacillus, which liquefied the preparation, 

 and on standing the ba/'illi settled to the bottom. The 

 supernatant fluid, which was clear, alkaline in reaction, and 

 contained dissolved " anthraxprotein," was filtered and 

 injected into animals without producing any effect. 1 



It must not be inferred from the above statements that 

 bacteria do not produce any ferments. Many of them do 

 form both diastatic and peptic ferments, which may retain 

 their activity after the bacteria have l>een destroyed ; but 

 there is no proof that in any case these ferments have any 

 causal relation to the disease. After the diseased process 

 has been inaugurated some of these ferments probably play 



1 We now know that if the supernatant fluid used in this experiment 

 had been injected in sufficient quantity death would have been produced 

 by the soluble chemical poisons. 



