HYPERSENSITIVENESS 477 



2. Animals are refractory following shock, or the injection of 

 desensitizing doses of antigen. This is due probably to the fact 

 that the antibodies attached to the tissue cells are exhausted or 

 saturated with antigen. This refractory state is called "imti- 

 atiaphylaxis" by Besredka and Steinhardt. 



3. AVlien the antibody content of the blood stream is high, the 

 animal may not develop symptoms following the injection of 

 antigen. It is thought that this is due to the union of antigen 

 and antibody in the blood stream and that, for this reason, the 

 former is not available to unite with antibody bound by the tis- 

 sues. This is called ''masked anaphylaxis." 



4. Animals may be protected by drugs. The literature on this 

 subject is reviewed by Aucr (1915). According to him, Fried- 

 l)crger' and Hartocli protected guinea pigs by injecting about 

 1 c.c. of saturated sodium chloride intravenously before the anti- 

 gen was administered. Biedl and Kraus prevented anaphylaxis 

 in dogs by injecting barium chloride. They also state that ani- 

 mals recovering from peptone shock are refractory to anaphy- 

 lactic shock. Likewise, atropine, adrenalin, chloral hydrate, and 

 even ether when administered to guinea pigs tend to reduce the 

 severity of the symptoms and prevent death in a fairly high per- 

 centage of cases. They have no effect upon the antigen-antibody 

 reaction, but affect tissue mechanisms only. 



5. Bronf enbrenner 's (1914, 1915) experimental results suggest 

 that a refractory state may occur when the antitryptic index is 

 high. 



While the symptoms of acute or protracted anaphylactic shock 

 exhibited b}^ all members of any one species are the same, it is 

 interesting to note that because of anatomical and physiological 

 differences in species each exhibits its own characteristic symp- 

 toms. These, along with a number of additional facts concern- 

 ing anaphylaxis, will be presented in the following brief dis- 

 cussion. 



Anaphylaxis in the Guinea Pig. — Acute Shock. — Symptoms of 

 acute shock in the guinea pig develop within one or two minutes 

 folloAving the intravenous or intracardial or intraperitoneal in- 

 jection of an adequate amount of antigen. The animal is quiet 

 for a few moments, then is restless and becomes excited, there 

 is a roughening of the hair, the pig sneezes, rubs its nose or ears 



