Effects of Magnesium upon Medulla. 105 



cnemius and the sciatic plexus was stimulated at about one minute 

 intervals by two consecutive shocks (make and break) from an 

 induction current. 



In agreement with the above mentioned statements, we found 

 that sodium chloride reduces indirect (curare-like action) and 

 reduces moderately also direct (Poljakofif) irritability. Both are 

 promptly restored by the addition of a small dose of calcium. As 

 a new fact we may mention that the irritability is more readily 

 abolished in cooled frogs. 



Although calcium restores indirect irritability when abolished 

 by sodium, it abolishes indirect irritability when injected primarily. 

 The dose necessary is considerably smaller than that of sodium for 

 the same effect. Again, the indirect irritability thus abolished by 

 primary infusion of calcium can be restored by sodium of which, 

 however, a larger dose is required than of calcium in a secondary 

 injection for a similar purpose. 



Calcium also reduces or abolishes direct irritability, which again 

 can be restored by sodium. The loss of indirect and direct irrita- 

 bility by calcium is not exactly parallel. Cooling seems to favor 

 the effects also of calcium. 



In these experiments neither sodium nor calcium exclusively 

 increased or decreased the irritability. Both depressed in primary 

 infusion and were mutually antagonistic in secondary infusions. 



53 (391) 



The effects of local applications of chloride and sulphate of 

 magnesium upon the centers in the medulla compared 

 with those of sodium chloride. 



By J. AUER and S. J. MELTZER. 



\_From the Department of Physiology and Pharmacology of the Rocke- 

 feller Institute for Medical Research.'^ 



The three salts were applied in molecular solutions to the 

 exposed medulla oblongata of rabbits. Both salts of magnesium 

 abolished sooner or later all the functions depending upon the 

 centers located in the medulla, the average time until a complete 

 effect took place being fifteen minutes. Respiration stopped and 



