CHAPTER VI 



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 phytotoxins. Of 

 these, the best known are ricin, abrin, 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. 



PHYTOTOXINS 2 



The chief phytotoxins are as follows: 



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



Abrin, from the seeds of Ahrus precatorius. 



Crotin, from the seeds of Croton tiglium. 



Robin, from the leaves and bark of the locust, Rohinia pseudoacacia. 



Curcin, from the seeds of Jatropha curcus. 



In their general properties all these substances are very similar and 

 may be considered together. They resemble proteins in many re- 

 spects, for they can be salted out of solutions in definite fractions 

 of the precipitate, are precipitated by alcohol, and are slowly de- 

 stroyed by proteolytic enzymes. For some time they were referred 

 to in the literature as toxalbumins, until Jacoby stated that, by com- 

 bining the salting-out method with trypsin digestion, he was able 

 to secure preparations of ricin and abrin that did not give the pro- 

 tein reactions. This seemed to place them in the same category 

 with bacterial toxins and enzymes, i. e., large molecular colloids, closely 

 resembling the proteins with which they are associated, but still not 

 giving the usual protein 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 Osborne, Mendel, and 

 Harris,-* however, does not support Jacoby's contention. They found 

 the toxic properties of ricin associated inseparably with the coagulable 

 albumin of the castor beans, and were able to isolate it in such purity 

 that one one-thousandth of a milligram (0.000001 gram) was fatal per 

 kilo of rabbit, and solutions of 0.001 per cent, would agglutinate red 



1 The poison in certain i>oas, especially Lnthijrns saluris, which causes severe 

 periphenil i)aialvsis, ('(ilhi/ri.sm) is believed to he an alkaloid. (liXill discussion by 

 Stockman, I'^diiih. Med. Jour., 1917 (10), 277). 



2 Ji.'suini' of literature by Ford, Cent. f. Hakt., 1913 (58), 129; Jacoby, Kolle 

 and Wass(M-inann's IIundbu(;Ii, 1913 (2), M.')3. 



•' Atiier. Jour, of IMiysiol., 190.") (14), 259. 



13S 



