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. These may be briefly considered as follows : 



PHYTOTOXINS 



The chief phytotoxins ^ are as follows : 

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

 Abrin, from the seeds of Ahrus prccatorius. 

 Crotin, from the seeds of C rot on tigliiim. 



Robin, from the leaves and bark of the locust, Bolinia pseudo- 

 acacia. 

 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 sohitions 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 pUice tliem in the same category 

 with bacterial toxins and enz.ymes, /. r., 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 tliis 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 isohite it in such purity 



1 Rr-suni(5 of litpi-atuiv hv Ford, Cent. f. Bakt., 101.3 (aS). 12!); .lacohv. Kollo 

 and Wasscrmann's Iland))uch. 1!)1,3 (2), 14;-).'?. 



2 Amcr. Jour, of Plivsiol., 100.') (14). 2.'i0. 



144 



