HYPERSEXSITIVENESS 497 



in heart rate, whereas in aiia|)hylaetie slioek 100 i)er eent of the 

 rabbits sliowed a decrease in heart rate (Bally, 1929). There is 

 also a differenee in Ihe dej^-ree to which tlie heart is slowed. Quile 

 similar results were obtained by Kabler and Sherwood in their 

 study of anaphylaxis in the cat. In the latter, when histamine 

 slows the heart, the rate is reduced only modei-ately, while in 

 anaphylactic shock the slowing is usually profound. 



3. When one com])ares tlie vascular clianges in the ear ol' the 

 ralj])it in histamine and anaphylactic shock, he ol)serves definite 

 diffei'ences in the intensity of the blanching reaction described 

 by Bally. The injection of histamine, even though a fatal dose 

 is given, never results in a complete obliteration of both capil- 

 laries and larger vessels since histamine is a capillary dilator. 

 On the other hand, one notes complete constriction of both capil- 

 laries and larger vessels ol" the ear in ral)bits during mild anaphy- 

 lactic shock. 



4. A comparison of kidney volume changes in the rabbit is also 

 of interest. In the series of rabbits which Bally injected with 

 histamine, none showed an increase, while 60 per cent of the in- 

 jections resulted in a decrease of kidney volume. In a compa- 

 I'able series in Avhich anaphylactic shock was studied, he reports 

 that 39 per cent showed an increase and only 13 per cent a de- 

 crease in kidney volume. Similar differences in intracystic pres- 

 sure in histamine and anaphylactic shock in the cat arc reported 

 by Kabler and Sherwood. 



5. If human idiosyncrasies are mediated l)y the same mechanism 

 as exi)erimental anaphylaxis, then another reason presents itself for 

 doubting the identity of histamine and the exciting agent causing 

 shock. It is quite well established that when one injects a snuill 

 amount of histamine into the human body an increase in 

 gastric acidity results. Tliis phenomenon is used in the diagnosis 

 of pernicious anemia where an aehylia is a characteristic finding. 

 Since in asthma and hay fever the gastric acidity varies from zero 

 to normal (Criep and Wechsler, 1931), it would appear that his- 

 tamine is not liberated in tlie body in these allergic conditions. 



6. Fein])erg and Bernstein (1940) in a review^ of the literature 

 on asthma and hay fever for 1939 conclude that more research is 

 needed before the histamine mechanism of allergy can be accepted. 



