TOXTNES. 3 



Although many of the bacterial substances formed in the most 

 different ways are products of secondary decomposition due to 

 obvious chemical reactions, yet beyond doubt some of them are 

 primary products of bacterial metabolism. 



Some of these metabolic products are more or less virulent 

 poisons. In this respect there is, in general, no difference 

 between pathogenic and non-pathogenic micro-organisms. 



Thus, even when substances of this kind are poisonous, they 

 have certainly nothing to do with the poisoning of an organism 

 through the invasion of bacteria, even assuming they are pro- 

 duced by pathogenic micro-organisms. Such poisons, for instance, 

 as neurine have their specific effects, whether produced by bac- 

 teria or by purely chemical reactions. Hence they must be 

 eliminated first of all from the definition of a toxine. 



In the second place, a series of substances has been prepared 

 by different processes from the dead cells of many species of 

 pathogenic micro-organisms. These are of a proteid nature, as, 

 for example, BUCHNER'S bacterial proteins, and are more or less 

 poisonous. But their toxic effects differ but little whatever their 

 origin. They never show a specific character, and never produce 

 symptoms resembling those of specific diseases. In addition to 

 this, the cell protoplasm of many bacteria contains toxic proteids 

 that cannot be isolated from the protein, and these are also non- 

 specific in their action. 



Excluding these, what is left on which to base the definition 

 of a toxine ? Certain pathogenic bacteria, when grown in a pure 

 cultivation, produce poisons that dissolve in the liquid nutrient 

 media, and can only be obtained in an undecomposed, concen- 

 trated, and imperfectly purified condition by the most careful 

 treatment substances which are not ptomaines and not proteids 

 (vide infra}. 



Such substances have been isolated, in particular, from pure 

 cultivations of the bacilli of diphtheria and tetanus, and they are 

 the true bacterial toxines in the narrower sense of the word. In 

 like manner all those more definite chemical poisonous substances 

 formed in the cells of higher animals and plants must be separated 

 from the toxines. 



The latter form a class of substances whose definition is found 

 in their nature and characteristic mode of action, irrespective of 

 their origin. 



Toxines are characterised in the first place by a sum of external 

 properties. Their chemical structure is absolutely unknown. 

 They are extremely unstable, and very sensitive towards even 

 slight chemical influences, and especially towards the action of 



