THE TOXINS 169 



such as the alkaloids and glucosides, and the toxins properly 

 speaking. The toxins alone produce antitoxins in the animal 

 treated by graduated doses, i.e., the antitoxins employed in 

 serotherapy. Antitoxins exist against ricin, abrin, and crotin, but 

 there are none' against solanin and saponin, which are glucosides. 

 The glucosides although capable of being fixed by sensitive 

 cells, do not produce anti-glucosides. Only those poisons 

 which are capable of giving rise to antitoxins can be regarded 

 as true toxins. 



Endotoxins. 



In contrast to the soluble toxins, the endotoxins are defined 

 as the poisons contained in the bodies of bacteria and not 

 spontaneously set free in cultures. Whereas the toxins are 

 secretions of living bacteria, the endotoxins, according to the 

 strict definition of R. Pfeiffer, are only set free by the 

 destruction of the bacterium. It is the protoplasm of the 

 bacterium itself which acts as a poison on absorption by' 

 the body. 



To bring the endotoxins into line with a well-known example, 

 one may compare them to the zymase of Buchner, the ferment 

 of yeast not excreted, or scarcely excreted, but set free by 

 grinding up with sand and expression of the juice under a 

 pressure of several hundred atmospheres. But this com- 

 parison is not to be taken to mean that the endotoxins are 

 diastases. 



Bacterial extracts have been produced by Buchner's process, 

 but nowadays endotoxins are obtained by simpler procedures. 

 MacFadyen grinds up the microbes at the temperature of 

 liquid air ; others subject the cultures to combined maceration 

 and shaking. Besredka takes young cultures, dries them, and 

 re-suspends them in saline solution. 



The endotoxins are distinct from the proteins ; the latter are 

 practically the same in the different species of bacteria. To 

 deserve their name they ought to be specific and to give rise 

 to antitoxins. 



