146 A MANUAL OF BACTERIOLOGY 



The production of the phenomena of disease by patho- 

 genic organisms has been ascribed to (1) the using up of 

 the oxygen which should go to the tissues ; (2) the using 

 up of the proteins of the body and of the food ; (3) the 

 effects of plugging of the vessels by the microbes ; and 

 (4) the effects of substances or " toxins," having a poisonous 

 action, formed by the microbes. Of these, the first three 

 are quite subsidiary, embolism and thrombosis being 

 perhaps the most important, and the toxins are the chief 

 factors which induce the pathogenic effects. These toxins 

 are substances of a very complex composition, probably 

 allied to the proteins ; in some instances they seem to be 

 of the nature of enzymes or ferments, and they are direct 

 products of the bacterial cells. The toxins of most 

 pathogenic organisms, e.g. typhoid, cholera, plague, etc., 

 are more or less integral parts of the bacterial cells ; they 

 are " endotoxins," and are not excreted to any extent 

 into the surrounding medium, but may gain access to it by 

 autolysis of some of the organisms. A few organisms, 

 notably Bacillus diphtherice and Bacillus tetani, produce 

 extra- cellular toxins which are found in the culture liquid. 

 The toxins are classified by Sidney Martin, 1 as follows 

 (see also p. 39) : 



(1) Poisons produced by the digestive or the destructive 

 action of bacteria on proteins in the culture medium. 

 Examples of these are the poisons of the Bacillus anthracis 

 and of the pus-producing staphylococci. 



(2) Poisons which are the result of the digestive or 

 destructive action of bacteria on proteins, but formed as 

 an excretion (the toxin) of the bacterium. The Bacillus 

 diphtherice is the best example of this. A similar com- 

 bination of poisons is found in snake- venom. 



(3) Poisons which are excretions only, such as those 

 produced by the tetanus bacillus. 



1 Manual of General Pathology, p. 76. 



