HYPERSUSCEPTIBILITY 363 



we may enumerate drop in blood pressure, fall of temperature, 

 diminution of leucocytes, increased flow of chyle, and certain meta- 

 bolic disturbances, the identity of which in different animal species 

 have not been worked out. 



In guinea pigs, as first demonstrated by Auer and Lewis, the 

 typical lung inflation which leads to respiratory death is ' due to 

 spasms of the muscles of the bronchioles. 



In rabbits, acute death is not respiratory, but is a circulatory 

 one, and has been shown by Coca 41 to be due to spasms of the 

 muscular coats of the arterioles of the pulmonary circulation, the 

 rabbit's lung during shock development remarkably increased pres- 

 sure against the passage of perfusion fluid. 



In dogs, acute anaphylactic symptoms have been localized in 

 the liver by Manwaring 42 and others. This peculiar physiological 

 difference in various animals in reaction to the same general 

 mechanism of injury has been difficult to understand, but recent 

 observations of Coca, Simonds, Huber and Koessler 43 and others 

 have been correlated by Wells into what seems to us a very rational 

 and likely explanation. Wells calls attention to the fact that acute 

 death in guinea pigs is due to spasm of the bronchial muscles, and 

 that anatomically the guinea pig has a very high development of 

 musculature in the bronchii, the smaller bronchioles being " prac- 

 tically nothing but muscular tubes." Similarly, Coca's findings in 

 relation to the pulmonary circulation of rabbits coincides with the 

 histological demonstration that the pulmonary arteries of the rabbit 

 show a marked muscular development. Simonds has shown that the 

 hepatic veins of dogs differ from those of all other animals in having 

 a highly developed musculature, and it would seem, as Wells points 

 out, as though the localization of acute changes in different organs 

 in the various animals were dependent upon fortuitous differences 

 in the anatomical distribution of the smooth muscle. He also points 

 out, as further evidence, that fatal reactions in man have occurred 

 only or most frequently in persons suffering from chronic pulmonary 

 conditions, chiefly asthma; and Huber and Koessler have shown 

 that asthmatic people develop a hypertrophy of the bronchial mus- 

 culature which in its final histology is closely analogous to that of 

 guinea pigs. 



41 Coca, Jour. Immimol., 4, 1919, 219. 



42 Manwaring, Jour, of Immimol., 2, 1917, 517. 

 "Huber and Koessler, Arch. Int. Med., 1921. 



