CHAPTER DC 



THE TOXINS OF THE HIGHER PLANTS AND ANIMALS AND THEIR ANTIBODIES. 

 FERMENTS AND ANTIFERMENTS. 



The toxins thus far studied were all secretory products of bacteria. This 

 power of forming toxins is not, however, limited to bacteria alone, as there is a 

 class of higher plants and animals that produce characteristic poisons 

 against which immunization can be undertaken and an antitoxic serum 

 obtained. Pollen toxin and snake poison are the only members of the 

 groups which bear any practical medical interest. The detailed study of 

 these plant toxins (Phytotoxin) and those of animal origin (Zootoxin) has, 

 however, greatly increased the theoretical knowledge of the phenomena of 

 reaction and immunity. 



Phytotoxins. 



The most important phy to toxins are: 



1. Ricin. 



2. Abrin. 



3. Crotin. 



4. Pollen. 



Ricin is a deadly poison, of which the smallest fractions of a milligram, 



Rjcin. are sufficient to kill rabbits. Like bacterial toxins, ricin requires for its 



action an incubation period of at least twenty-four hours. The typical 



post-mortem findings consist of redness and swelling of Peyer's patches. Ricin is a 



hemo toxin; if mixed, as an emulsion, with red blood-cells, the erythrocytes sink to the 



bottom and are agglutinated. 



Ehrlich succeeded in immunizing animals against ricin by first giving it to them per 

 os in increasing doses for a long period of time, and later on by subcutaneous injection. 

 The antitoxic serum thus produced neutralizes the poisonous action of ricin both in vivo 

 and in vitro. 



Abrin, a vegetable poison, is obtained from jaquirity (Abrus precatorius) 

 Abrin. and in its action closely resembles ricin, but is less poisonous. It is a 

 marked irritant of the conjunctiva and was at one time employed in cases 

 of trachoma. 



Roemer found that by repeated instillation of abrin in to -the same conjunctival sac, 

 no reaction was ultimately obtained (local immunity), while the conjunctiva of the other 

 eye retained its susceptibility. If the instillation was continued for a long period of time, a 

 " general immunity" was attained which extended to the conjunctivse of both eyes. As 

 a result, in the serum of such animals anti-abrin could be demonstrated. 



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