250 PROTEIN POISONS 



when barium chloride is given before the reinjection, the 

 latter does not cause a fall in blood pressure. Still more 

 striking is the fact that when barium chloride is given in 

 anaphylactic shock, as the pressure rises the symptoms 

 disappear; also, when this substance is given in doses which 

 cause in normal animals a marked and peristent increase 

 in pressure, before the reinjection, the latter induces no 

 anaphylactic symptoms. That the animals upon which 

 these observations were made were in a sensitized state 

 was proved by inducing passive anaphylaxis in normal 

 animals with their sera. It will be seen from the above 

 that in experimental anaphylaxis in dogs, barium chloride 

 is efficient both as a preventive and a curative agent. 



The antagonistic action of barium chloride demonstrates 

 the peripheral genesis of anaphylactic vasodilatation, but 

 it does not wholly settle the question as to whether the 

 dilatation is due to the effect of the poison on the nerves 

 or on the smooth muscle. The failure of adrenalin and 

 the success of barium chloride in raising the pressure in 

 anaphylactic shock render it highly probable that the 

 anaphylactic poison lowers the blood pressure by paralysis 

 of the smooth muscle of the vessel walls. It seems quite 

 certain that barium chloride and the anaphylactic poison 

 act upon the same peripheral apparatus, that the action of 

 the former is stimulating, and that of the latter is paralyzing, 

 and the former is the stronger and able to prevent or replace 

 the latter. 



Having established the fact that fall in blood pressure 

 is a marked and constant result of the anaphylactic poison, 

 the symptoms become easily explainable. The resulting 

 anemia of the brain explains the disturbances of respiration, 

 the retching, the expulsion of urine and feces, the great 

 depression and muscular weakness, and the speedy recovery, 

 when death does not result. 



Biedl and Kraus give as additional phenomena of 

 anaphylactic shock the following: (1) On reinjection 

 the coagulability of the blood falls markedly or wholly 

 disappears. Before the reinjection is made the blood of a 



