CHAPTER IX. 



THE TOXINS OF THE HIGHER PLANTS AND ANIMALS AND THEIR ANTI- 

 BODIES. 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. Aside from snake poison, the members of this group 

 bear little 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. 



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



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



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



postmortem 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 into 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 conjunctivas of 

 both eyes. As a result, in the serum of such animals antiabrin could be demonstrated. 



95 



