NEGATIVE CATALYSTS 105 



property of reproducing itself in the manner indicated under the 

 heading of auto-catalysis (see p. 112). 



The theory of infection held at the present day includes as 

 an axiom that all infection must be carried by micro-organisms 

 or parasites. Now, although this has been incontrovertibly 

 demonstrated in many cases, in just as many others, and these 

 including the most common infectious diseases, in spite of in- 

 numerable attempts no causal connection between any definite 

 parasite or micro-organism has been shown to exist. 



If the above-mentioned axiom is granted, then it follows that 

 vaccine prepared with chloroform must contain an undemon- 

 strable living germ, but otherwise the experimental evidence 

 is far more strongly in favour of the virus being an enzyme, re- 

 producing itself in the manner described under auto-catalysis. 



At any rate for the present, the case may serve as an example 

 of how difficult it often is to decide whether a given action is the 

 result of an enzyme or a living cell, because the same agencies 

 which affect one similarly affect the other. 



NEGATIVE CATALYSTS 



The catalysts which we have hitherto been considering are 

 those which, by their action in diminishing resistance, increase 

 the velocity of a reaction, but a number of substances are known 

 which increase the resistance and so diminish the velocity of the 

 reaction without being changed themselves in the process. Such 

 bodies have been termed by Ostwald negative catalysts. In the 

 language of our formulae these bodies diminish the value of Jc, the 

 constant of reaction velocity. That these substances are truly 

 catalytic in their action is demonstrated by the extremely minute 

 quantities necessary to slow the reaction in comparison with the 

 quantities of substratum acted upon. Thus Bigelow has shown 

 that the presence of such a minimal trace of mannite as 

 0-000,001,4 grm. per cubic centimetre reduces the velocity of 

 oxidation of 800 times as great an amount of sodium sulphite in 

 solution by one-half, and S. W. Young has shown that the oxidation 

 of stannous chloride or sodium sulphite is similarly reduced by 

 mere traces of many organic substances, such as nicotine, brucine, 

 morphine, quinine, aniline, mannite, and potassium cyanide. As 



