170 MICROBES AND TOXINS 



It is in the cholera vibrio, the plague bacillus, the typhoid 

 bacillus, and the bacillus of dysentery that they have been 

 chiefly sought for and thought to have been found. It is 

 necessary to employ this qualified method of .expression, 

 because their definition and even their existence is still 

 disputed. This chapter in the physiology of bacteria contains 

 many uncertainties, and the facts observed cannot always be 

 made to agree. 



The endotoxins obtained by different workers from the same 

 bacterium do not seem to possess the same properties, 

 especially from the point of view of the toxic dose and the 

 resistance to temperature ; but it is also well known that with 

 tetanus toxin different workers do not obtain equal specimens 

 either. 



Between the endotoxins described as having the same 

 general characters there exist differences which are not to be 

 found between the diphtheria and tetanus toxins ; thus the 

 plague endotoxin is destroyed by heat from about 75° C. 

 onwards, whereas the typhoid endotoxin resists 127° C. (accord- 

 ing to Besredka). But physical differences are known to exist 

 between the diphtheria and tetanus toxins also, which, though 

 less striking, are none the less real. 



The dysentery endotoxin is easily obtained, the typhoid 

 endotoxin less easily, the cholera endotoxin with great 

 difficulty. 



The following are the principal points disputed. 



I. The fundamental phenomenon on which depends the 

 existence of specific endotoxin is the toxicity of the bacterial 

 bodies themselves. The nature of the bacterial bodies must 

 first be agreed upon, and no agreement will be reached unless 

 young bacteria are taken, avoiding as much as possible the 

 alterations caused by manipulations; however carefully or 

 cautiously conducted. Pfeiffer is inclined to regard with some 

 suspicion the endotoxins which accumulate spontaneously 

 in old cultures, considering them as products of a destruction 

 of the bacteria, which is accompanied by chemical alterations 

 (fermentative), of the details of which we are ignorant. These 



