THE TOXINS PRODUCED BY BACTERIA 193 



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 BACTERIA. 



Early Work on Toxins. We know that bacteria are capable 

 of giving rise to poisonous bodies within the animal body and 

 also in artificial media. We know, however, comparatively little 

 of the actual nature of such bodies, and therefore we apply to 

 them as a class the general term toxins. The necessity for 

 accounting for the general pathogenic effects of certain bacteria, 

 which in the corresponding diseases were not distributed through- 

 out the body, directed attention to the probable existence of 

 such toxins ; and the first to systematically study the production 

 of such poisonous bodies was Brieger. This observer 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 re- 

 produced 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 Roux and Yersin to obtain, in the case of the 

 b. diphtherias, a solution containing a toxin which reproduced 

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

 further inquiry as to the nature of this toxin. An attempt on 

 the part of Brieger and Fraenkel to obtain a purified diphtheria 

 toxin by precipitating bouillon cultures by alcohol (the product 

 being denominated a toxalbumin) did not greatly advance 

 knowledge on the subject, and further investigation soon showed 

 that specific toxins can be isolated from but few bacteria. 



General Facts regarding Bacterial Toxins. The following 

 may be regarded as the chief facts regarding bacterial toxins 

 which have been revealed by the study, partly of the bodily 

 tissues of animals infected by the bacteria concerned, partly of 

 artificial cultures of these bacteria. In dealing with these it is 



