HYPERSENSITIVENESS 479 



or segments of small intestine. The contractions of the uterine 

 horn are recorded hy means of a light heart lever attached at 

 one end by means of a thread to the upper end of the uterine 

 horn, while the other end of the heart lever produces a kymo- 

 graphic tracing on smoked paper. As previously mentioned, it is 

 necessary to demonstrate desensitization lo differentiate between 

 toxic and anaphylactic reactions. The latter phenomenon is 

 called quite frequently "the smooth muscle reaction of Dale." 

 Stoland and Sherwood (1923) showed that when adequate doses 

 of atropine are added to the bath, specific reactions are prevented. 

 In their opinion Tyrode's solution containing dextrose and half 

 the usual amount of calcium is superior to either Locke's or 

 Ringer's solution. 



Anaphylactic Shock in the Rabbit. — The first extensive studies 

 of anaphylaxis in rabbits were carried out by Arthus (1903). 

 When a sensitized rabbit is given an adequate intravenous injec- 

 tion of antigen, it may develop symptoms before the injection is 

 completed or it may remain quiet for one or two minutes and 

 then become excited, run aimlessly about, and die suddenly with 

 its head retracted and eyes in exophthalmus. This is acute fatal 

 anaphylactic shock in the rabbit. The cause of death has been 

 studied by Auer, Coca, Airila and others. They have apparently 

 shown that it is due to right heart failure caused by an increase 

 in resistance to blood flow through the pulmonary circuit. The 

 lungs are observed to be completely collapsed when the chest is 

 opened. Arthus observed a prolongation of the clotting time of 

 the blood. Bally (1929), working in our laboratory, carried out 

 extensive physiological studies of anaphylaxis in rabbits. PTe 

 summarizes some of his results as follows: 



''1. The characteristic blood pressure response is an increased 

 pressure followed by a decreased pressure which slowly returns 

 to normal in the case of recovery. 



''2. There is a peripheral circulatory response shown by the 

 'blanching reaction' of the ear to be much more pronounced than 

 in either peptone or histamine shock. 



"3. There is a tachycardia during the blood pressure increase 

 which gives way to a bradycardia during the blood pressure 

 fall and persists after the ])lood ]>ressure has reestablished itself. 



