CHAPTEK VIII 

 PHYTOTOXINS AND ZOOTOXINS 



THE production of substances possessing the essential features 

 of true toxins is by no means limited to the bacterial cell. In 

 the plant kingdom such substances are formed, and called phyto- 

 toxins. Of these, the best known are ricin, abriu, crotin, and 

 robin. Among the toxins of animal origin, zootoxins, are the 

 venoms of poisonous snakes, lizards, spiders and scorpions, and 

 the serum of eels and snakes. These may be briefly considered 

 as follows : 



PHYTOTOXINS 



The chief phytotoxins l are as follows : 



Ricin, from the castor-oil bean (Ricinus communis). 



Abrin, from the seeds of Abrus precatorius. 



Crotin, from the seeds of Croton tiglium. 



Robin, from the leaves and bark of the locust, Robinia pseu- 



doacacia. 



In their general properties all these substances are very similar 

 and may be considered together. They resemble proteids in 

 many respects, for they can be salted out of solutions in definite 

 fractions of the precipitate, are precipitated by alcohol, and are 

 slowly destroyed by proteolytic enzymes. For some time they 

 were referred to in the literature as toxalbumins, until Jacoby 

 stated that, by combining the salting-out method with trypsin 

 digestion, he was able to secure preparations of ricin and abrin 

 that did not give the proteid reactions. This seemed to place 

 them in the same category with bacterial toxins and enzymes, 

 i. 6., large molecular colloids, closely resembling the proteid.s 

 with which they are associated, but still not giving the usual 

 proteid reactions. Because of their great similarity to bacterial 

 toxins this seemed a very probable description, and it has been 

 generally accepted. More recent work by Osborue, Mendel, 

 and Harris 2 however, does not support Jacoby' s contention. 

 They found the toxic properties of ricin associated inseparably 



1 Ke*sume" of literature by Jacoby, Biochem. Centralblatt, 1903 (1), 289. 



2 Amer. Jour, of Physiol., 1905 (14), 259. 



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