DISEASE, INFECTION, AND RESISTANCE 301 



It has long been known that certain substances, par- 

 ticularly certain proteins, are poisonous to certain indi- 

 viduals. There are some persons, for example, who cannot 

 eat eggs without being poisoned thereby. The specific 

 phenomenon, however, was not carefully investigated until 

 after certain accidental observations were made upon the 

 conduct of guinea pigs. In the study of the standardization 

 of antitoxin attempts were made to use guinea pigs a second 

 time as test animals, that is, animals which had received 

 doses of antitoxin and toxin and had recovered were later 

 tested out to determine whether or not they might be 

 utilized a second time for standardization. It developed, 

 however, that almost invariably a second injection of anti- 

 toxin proved fatal. This led to a study of the effect of 

 injecting pure proteins into guinea pigs. It was found 

 whenever a dilute solution of a protein is injected under the 

 skin of a guinea pig or introduced into the blood stream, the 

 animal then allowed to remain without subsequent injection 

 for a period of two weeks or more, that a second injection 

 made after the end of this period resulted in the develop- 

 ment of a certain reaction which has been termed the ana- 

 phylactic shock. For example, a guinea pig may be 

 injected with a small quantity of egg white. It will show 

 no untoward reactions, will remain apparently healthy and 

 vigorous, but when injected intraperitoneally or intra- 

 venously two weeks or more later with a similar solution of 

 egg white there will be a rapid development of severe symp- 

 toms. The animal will show difficulty in respiration. It 

 will urinate and defecate rapidly. It will usually scratch 

 its nose with its front paws, thus showing evidence of diffi- 

 culty in respiration. It may finally develop convulsions, 

 fall over on its side and die within a few minutes after 

 injection. What was, upon the first injection, a nonpoison- 

 ous substance is found upon a second injection to become a 

 deadly poison for the guinea pig. An animal which has 



