TOXINS. 179 



An important test for the pathogenic signifi- 

 cance of a toxin lies in its ability or inability to 

 cause the formation of an antitoxin which is 

 efficient in the treatment of an infection by the 

 corresponding organism. This is not the case 

 with the toxins just mentioned. However, one 

 should not place too much importance on such a 

 test, for it is possible that we are not able on 

 artificial culture media to obtain the toxin in 

 such concentration that the production of an effi- 

 cient antitoxin is possible. 



There is a large class of organisms the members intraceiiniar 

 of which apparently do not produce soluble toxins ; 

 such organisms, however, cause highly toxic diseases 

 (e. g., typhoid, cholera, plague). The dead or 

 ground-up bodies of such bacteria are very toxic; 

 also when the germs disintegrate by a process of 

 autolysis or self-digestion the culture medium be- 

 comes toxic because of the cell contents which are 

 set free. Such organisms are said to contain in- 

 tracellular toxins or endotoxins. In infections by 

 them it is supposed that toxic symptoms are pro- 

 duced when a pathogenic amount of the intracel- 

 lular toxins is liberated by the bacteriolytic action 

 of the body fluids or cells (phagocytes). 



Nothing is known of the nature of such toxins. 

 They certainly are very different from the soluble 

 toxins of diphtheria and tetanus, since immuniza- 

 tion with them has not as yet resulted in the pro- 

 duction of efficient antitoxins. In spite of this 

 fact, however, it is none the less probable that 

 they are the disease-producing constituents of the 

 organisms. Buchner gave the name of "plasmin" 

 to the cell juice which he was able to express from 

 some micro-organisms. 



