118 INFECTION 



toxins contained within the cell-bodies, and have been found to possess 

 less toxicity. 



Beside these toxins, some streptococci produce a hemolysin which 

 may be conveniently observed by cultivation of the organisms upon 

 blood-agar plates. This hemotoxin is partly responsible for the san- 

 guineous character of a streptococcus exudate. 



TOXINS OF THE HIGHER PLANTS AND ANIMALS . 

 PHYTOTOXINS 



As has previously been mentioned, the power of forming toxins is not 

 confined to bacteria alone. There is a class of higher plants and ani- 

 mals that produces characteristic poisons against which immunization 

 can be undertaken and an antitoxic serum obtained. Those of most 

 interest medically are pollen toxin and snake poison. 



The most important plant toxins (phytotoxins) are ricin, abrin, 

 crotin, and pollen. All possess more or less toxic qualities; the first 

 three either agglutinate or hemolyze the corpuscles of certain animals. 

 Antitoxic serums have been prepared that will neutralize the respective 

 toxins, and this factor constitutes the most important evidence of their 

 toxin-like character. 



General Properties. These toxins resemble proteins in many re- 

 spects. Jacoby, however, has placed them in the same class as bacterial 

 toxins and enzymes, i. e., large molecular colloids closely resembling the 

 proteins, but still not giving the usual protein reaction. More recent 

 work by Osborne, Mendel, and Harris, 1 however, does not support 

 Jacoby's view. These observers found the toxic properties of ricin 

 inseparably associated with the coagulable albumin, and were able to 

 isolate it in such strength that ToVo milligram was fatal per kilo of rabbit, 

 and solutions of 0.001 per cent, would agglutinate red corpuscles. 



Relation to Immunity. The phytotoxins, since they obey the same 

 laws as bacterial toxins, have been very serviceable in the study of im- 

 munity; they are more stable than the latter, and can be handled in 

 more exact and definite quantities. They have apparently the same 

 haptophore and toxophore structure as bacterial toxins; antitoxins are 

 readily produced by immunizing animals, and seem to be specific for the 

 toxins; in fact, Ehrlich made his earliest observations on the specificity 

 and quantitative factors in toxin-antitoxin immunity from a study of 

 these plant toxins. 



. Jour. Physiol., 1905, 14, 259. 



