186 THE TOXINS PEODUCED BY BACTERIA 



common. The symptoms due to disturbance or abolition of the 

 functions of secretory glands also constitute an important group, 

 forming, as they do, a striking analogy to what is found in the 

 action of various drugs. 



These tissue changes and symptoms are given only as illus- 

 trative examples, and the list might easily be greatly amplified. 

 The important fact, however, is that nearly all, if not quite all, 

 the changes found throughout the organs (without the actual 

 presence of bacteria), and also the symptoms occurring in infec- 

 tive diseases, can either be experimentally reproduced by the in- 

 jection of bacterial poisons or have an analogy in the action of 

 drugs. 



The Toxins produced by Bacteeia. 



Early Work on Toxins. — The first to study systematically 

 the production of bacterial toxins was Brieger, who isolated from 

 putrefying substances, and also from bacterial cultures, nitrogen- 

 containing bodies, which he called ptomaines. Similar bodies 

 occurring in the ordinary metabolic processes of the body had 

 previously been described and called leucomaines. Ptomaines 

 isolated from pathogenic bacteria in no case reproduced the 

 symptoms of the disease. The methods by which they were 

 isolated were faulty, and they have therefore only a historic 

 interest. The introduction of the principle of rendering fluid 

 cultures bacteria-free by filtration through unglazed porcelain, and 

 its application by Koux and Yersin td obtain, in the case of the 

 b. diphtherias, a solution containing a toxin which reproduced 

 the symptoms of this disease (vide Chapter XVI.), constitute 

 the starting-point of modern work on the subject. 



General Facts regarding Bacterial- Toxins. — In dealing with 

 the action of toxins it is necessary to distinguish between the 

 effects produced by the actual constituents of the bacterial 

 protoplasm (intrabacterial toxins, endotoxins) and those which in 

 a few bacteria are traceable to soluble substances passing out 

 into the media in which these bacteria may be growing (extra- 

 bacterial toxins, exotoxins). The former are concerned in the 

 action of by far the greater number of pathogenic bacteria; 

 the latter account for the pathogenic processes originated in a 

 limited number of cases of which diphtheria and tetanus are the 

 most important. This distinction is important as, in consequence 

 of these last two diseases having had much attention directed 

 towards them early in the history of research on ! the subject, 

 there has hitherto been too much tendency to take for granted 

 that poisons of a similar constitution are concerned in all cases 



