28 



Scientific Proceedings (36). 



diately reestablished, and it was possible to extirpate leisurely the 

 anterior wall of the part of the aorta that had been tubed and to 

 substitute for it a segment of vena cava preserved in cold storage. 

 This operation lasted twenty-four minutes. The tube was then 

 taken out. The animal recovered without incident. He died 

 suddenly of hemorrhage twelve days after the operation. The 

 accident was due to a fault of technique in preserving the veins in 

 cold storage. 



These experiments show that operations on the thoracic aorta 

 need not be very dangerous, and that, by Meltzer's method, they 

 are as simple as abdominal operations. 



18 (428) 



The mutual antagonistic life-saving action of barium and 

 magnesium. A demonstration. 



By DON R. JOSEPH and S. J. MELTZER. 



[From the Department of Physiology and Pharmacology of the 

 Laboratories of the Rockefeller Institute for Medical 

 Research^ 



For rabbits, 1.2 grams of magnesium sulphate per kilo body- 

 weight are invariably fatal in intramuscular injection ; they usually 

 die in less than twenty minutes. The rabbit to the right {A) re- 

 ceived such a dose and has been dead for some time. The rabbit 

 in the middle [B) received a similar dose of magnesium and is still 

 alive ; it breathes regularly. This animal received also an intra- 

 venous injection of barium chloride, which is the cause of its sur- 

 viving the fatal dose of magnesium. 



By a special study we are enabled to state the mode of the 

 antagonistic action of the barium which is this : the fatal action 

 of magnesium is due to a paralysis of respiration and barium 

 counteracts just this effect of magnesium. It differs from the 

 antagonistic action of calcium inasmuch as calcium antagonizes all 

 the effects of magnesium, while barium picks out only the respira- 

 tion, the animal remaining anesthetized and paralyzed. 



This surviving rabbit {B) illustrates, however, also another re- 

 sult. The rabbit to the left (6") is dead from a dose of barium 



