ENDOTOXINES AND PROTEINS. 65 



the striking symptoms of poisoning that appear in the spontaneous 

 infection of man with cholera are also due to the absorption of 

 poisons, endotoxines, set free through the solution of the cholera 

 vibrio. In his opinion, endotoxines are thus the main effective 

 poison in cholera and other infectious diseases, such as typhus, 

 &c., that behave in an analogous manner. In support of this 

 view, that in these infectious diseases we have only to deal with 

 the bacteria as such, and the poison contained in their cells, and 

 not, as in the case of diphtheria, &c., with a soluble poison that 

 can be separated from the cells, but of whose presence in the 

 human subject we cannot speak with certainty, as pointed out 

 above ; in support of this view we have the phenomena that 

 occur in the disappearance of these diseases and in immunisation 

 against these bacteria, and the substances that are then found in 

 the serum. Thus we have seen that in cholera, &c., only bacteri- 

 cidal substances are present; but such exclusively bactericidal 

 substances only occur, as WASSERMANN was able to show in the 

 case of B. pyocyaneus, when there has been absorption of consti- 

 tuents of the cell-substance of the bacteria, while toxines invariably 

 cause a simultaneous formation in the serum of antitoxic sub- 

 stances, and substances possessing specific bactericidal powers. 



Bacterial Proteins. When bacteria that produce soluble 

 poisons are freed as completely as possible from those poisons, 

 there will still remain substances that belong to the cell 

 material. These substances, too, have a physiological action, 

 producing inflammation, aseptic abscesses, and necroses at the 

 point of application, as well as slight general symptoms, such as 

 fever, faintness, headache, &c. 



The same effects are also produced by the albuminous sub- 

 stances prepared by chemical methods from the cells of the 

 bacteria, and termed bacterial proteins, as first proposed by 

 BUCHNER. They are obtained by different methods, of which 

 those chiefly employed are extraction with superheated water in 

 autoclaves, simple boiling with water, and extraction with dilute 

 alkalies. To these have recently been added those methods, due 

 to KOCH and BUCHNER, in which the bacteria are first triturated 

 either in the moist or dry condition, with, in some cases, the aid 

 of hydraulic pressure, in order to obtain their contents. 



In this way a long series of bacterial proteins has been 

 obtained, which, although differing in some particulars, produce 

 practically similar effects. We shall frequently meet with them 

 in the special part, where, too, will be found references to the 

 most important researches on this subject. 



It is unnecessary to describe these proteins in detail here, for 



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