260 
The Antagonistic Action of Calecum upon the Inhilitory Effect 
of Magnesium. 
By 8S. J. MELTZER and JOHN AUER. 
(Communicated by Professor E. H. Starling, F.R.S. Received March 10,— 
Read April 2, 1908.) 
(From the Department of Physiology and Pharmacology of the Rockefeller Institute 
for Medical Research.) 
Calcium and magnesium are chemically closely related elements. They 
are also close companions in the tissues of the animal body. It is the 
prevailing view that the physiological effects of both elements are similar 
in character. Many physiologists are at present of the opinion that 
calcium as well as magnesium exerts an inhibitory influence in the functions 
of the animal body. Loeb published, in 1899, his observations of the 
inhibitory action of calcium upon the twitchings of the frog muscles brought 
on by solutions of sodium chloride.* It was then assumed by Loeb that 
all the members of the group of alkali earths possess inhibitory properties, 
including, at first, even barium. In the numerous subsequent papers by 
Loeb and his pupils, the discussion turned, however, essentially around the 
inhibitory effect of calcium. 
As to magnesium, we have within the last few years published several 
studies in support of the hypothesis that magnesium salts favour inhibitory 
processes. The first fact which gave rise to that hypothesis was demonstrated 
in 1899 to the American Physiological Society, when an _ intracerebral 
injection of a.few drops of a solution of magnesium sulphate caused a state 
of paralysis in a rabbit, while the injection of other solutions brought on 
convulsions. 
In a series of recent studies which we have carried out upon the relations 
of the effects of calcium to magnesium, many facts came to light which 
demonstrate unmistakably that calcium is the most available agent to 
neutralise inhibitory effects of magnesium. We shall not enter here upon 
details; we wish only to report the following striking and instructive 
experiment. 
* (Note by E. H. Starling—The inhibitory action of calcium salts on the twitching 
brought on by sodium chloride solutions was observed by Dr. Ringer, F.R.S., many years 
before Loeb, and is fully described by him ina paper in the ‘Journal of Physiology,’ 
vol. 7, p. 291, 1886. In reference to the subject of the present communication, it is 
interesting to note that Ringer observed a similar antagonism between barium and 
calcium (vide ‘ Practitioner,’ vol. 31, p. 81, 1897).) 
