Combined action of magnesium and ether;evidence of a central effect of magnesium

We have shown about eight years ago that magnesium sulphate is capable of causing a profound depression in animals. After an injection of a proper dose of a solution of a magnesium salt the animal loses for some time, all reflexes and signs of sensibility, while the respiration remains intact. Several years before it was found (M.) that a condition similar to this can be produced by an intracerebral injection of two or three drops of a 5 per cent. solution of magnesium sulphate, while the injection of hypertonic solutions of other salts caused convulsions. On the basis of both experiences we assumed as a working hypothesis that magnesium favors an inhibition of the entire nervous system. We designated the depressed condition of the animals as anesthesia, which implied that the central nervous system was also affected. This interpretation has not been accepted by Wiki. He called attention to experiments of Binet and of his own to the effect that magnesium salts paralyze the motor nerve endings, and he assumed that in our experiments the animals were merely paralyzed and had not lost any sensation; in short, magnesium acts, according to Wiki, like curare, although he admits the significant difference that curare paralyzes the respiratory motor nerves before the motor nerves of the other parts of the body, while magnesium paralyzes all other motor nerves before it attacks the motor nerves concerned in the respiration. The statement that magnesium paralyzes motor nerve endings is perfectly correct; we have seen it ourselves numerous times.

While it is true that many other inorganic salts have also a curarelike action upon the motor nerve endings, it has to be admitted that the effect of magnesium salts upon the motor nerve endings exceeds that of any of the other salts.