Prevention of Proteotoxin Shock. 205 



observations of Ritz. It must be remembered that, as Fried- 

 berger and Hartoch pointed out, the protective action of salt is 

 a limited one and if the amount of antigen given at the second 

 injection or if the amount of proteotoxin used is much above the 

 minimal fatal dose, the poisoning is so acute and powerful that the 

 protective effects of the salt are entirely masked. We had con- 

 siderable difficulty at first in obtaining satisfactory experiments 

 because of our failure to appreciate this relation, but when the 

 toxic dose did not materially exceed the minimal fatal dose there 

 was no difficulty in determining the protective effect of salt in 

 guinea-pigs injected with proteotoxin. Preliminary tests showed 

 that guinea-pigs ranging in weight from 165 to 200 grams could 

 withstand, without serious effects, the injection of 1.5 c.c. of 30 

 per cent, salt solution into the external jugular vein. The blood 

 oozing from the injection wound was a bright brick red. This 

 striking change in color can not at present be explained. The salt 

 solution must be injected very slowly, and we allowed from 1 to 12 

 minutes for its introduction. An interval of 2 minutes was allowed 

 between the injections of the salt and the proteotoxin. Though 

 this interval may not be absolutely necessary our most successful 

 experiments were obtained when it was observed. The following 

 three experiments are examples of the striking protective action 

 exerted by the sodium chloride. 



Experiment I. 



Injections were made into the jugular veins; usually the salt 

 solution was injected at a point close to the maxilla, a ligature 

 applied and the proteotoxin injected proximally into the same 

 vein. The injections of salt were carried out slowly, from one to 

 one and a half minutes taken for the introduction of one cubic 

 centimeter. 



From these experiments it is plain that the toxic action of the 

 proteotoxin (anaphylatoxin) is prevented by the immediately 

 preceding injection of enough sodium chloride to render the blood 

 of the animal hypertonic. 



Having confirmed the experiments of Ritz it was next necessary 

 to determine the mechanism of this protection. 



It is well known that during anaphylactic shock violent con- 



