Influence on American Physiology. 



3i 



magnesium sulphate had attracted his attention as far back as 

 1899, an d he reported upon it incidentally in a communication to 

 the American Physiological Society. But in 1904-05, influenced 

 again by his general conception of the importance of the inhibitory 

 processes he took up with Auer a careful physiological study of its 

 action. The results were most interesting and important. When 

 given subcutaneously in certain doses the magnesium sulphate 

 produces a condition of complete unconsciousness and muscular 

 paralysis or relaxation, which is reversible, in the sense that when 

 the animal is given proper care it recovers. Later he was able to 

 show that out of this condition of profound depression or inhibition 

 the animal may be restored to complete consciousness and motil- 

 ity with miraculous suddenness by the intravascular injection of 

 small amounts of calcium chloride. No one who was fortunate 

 enough to see this demonstration as given by Dr. Meltzer will for- 

 get its dramatic effect upon his audience. A healthy vigorous 

 rabbit was brought quickly to a condition of complete immobility 

 and apparent death by the magnesium sulphate and then even 

 more suddenly raised from the dead and restored to its normal 

 tranquil existence by the injection of some calcium chloride. 

 Meltzer and his collaborators investigated various phases of 

 this action of magnesium sulphate and all of the results obtained 

 tended to strengthen in his mind the conviction that in magnesium 

 he had discovered the element in the body that is especially con- 

 cerned in the processes of inhibition. The antagonistic action of 

 the calcium although exhibited in such a striking way was not in 

 his opinion specific. His own experiments in connection with the 

 results reported by other observers led him to the general view that 

 calcium serves to balance the abnormal activity of the other 

 kations, potassium, sodium and magnesium, whether this ab- 

 normal action is in the direction of excitation or of inhibition. 

 Modern work upon the physiological significance of the inorganic 

 constituents of the body fluids which was begun in Ludwig's 

 laboratory, but was given its main impetus by the striking con- 

 tributions of Ringer had concerned itself chiefly with the salts 

 of potassium, sodium and calcium, which alone seemed to be suffi- 

 cient to maintain normal conditions of irritability. Meltzer's 

 work has shown that magnesium also has its place in this ancient 



