SHOCK 45 



lated that this substance, or a similar substance, is 

 liberated when tissues are injured. As will be shown 

 in our subsequent discussion, it is improbable that 

 cytost and histamine are identical. 



Bayliss, Cannon and their associates have shown in 

 a fashion analogous to that employed by the author 

 that crushing the thigh muscles of anesthetized cats 

 will induce shock in the animals. Cannon (1923) 

 showed further that if circulation in the animal's legs 

 is arrested by clamping the abdominal aorta, no symp- 

 toms of shock appear until the release of the aortic 

 clamp. 



These results are in agreement with those of the 

 author's experiments, wherein he utilized a tourniquet 

 to prevent circulation in the animal's limbs. Again, 

 by means of a parabiotic union of the circulation of 

 two animals. Cannon has shown that the production 

 of an injury in one animal leads to a state of shock 

 in both animals. 



This type of experiment has also been conducted by 

 the writer (unpublished) , but in view of the fact that 

 much the same result is achieved by the injection of 

 the blood serum or tissue juices of the injured animal 

 into a normal animal, the writer has felt it unneces- 

 sary to adopt the elaborate technique of parabiotic 

 experiments. Furthermore, in such an experiment, 

 the "normal" animal may well be rendered hyper- 

 sensitive to the shock reaction because of the tissue 

 damage incident to the establishing of the parabiosis. 



The validity of the writer's contention concerning 

 the toxic nature of shock has been recognized by Jean- 

 neney (1921), Hartmann (1922), and Limousin 

 (1923). 



