Combined Action of Magnesia and Ether. 159 



change of erythrocytes in layers of varying thickness is in accord- 

 ance with the principle of dichromatism. It is possible to con- 

 struct a thin wedge of solid oxyhemoglobin and observe the thick- 

 ness at which the color change occurs. In such a wedge at a 

 thickness of 1 .3 n and less the color is identical with that of a single 

 layer of red blood corpuscles. Above 1 .3 ju. a distinct reddish tinge 

 is noticeable, increasing with the thickness of the wedge to a deep 

 pure red. In this experiment the color is the same in parallel or 

 convergent light. This rules out the influence of the stroma and 

 the surface curvature on the color of the red blood corpuscles. 

 Finally, small (microscopic) crystals of oxyhemoglobin (second 

 crystallization) are of the same color as the red blood corpuscles, 

 while larger (i. e., thicker) crystals are bright red. 



99 (795) 



Combined action of magnesium and ether; evidence of a central 

 effect of magnesium. 



By S. J. Meltzer and John Auer. 



[From the Department of Physiology and Pharmacology of the 

 Rockefeller Institute.] 



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 

 intra-cerebral 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 interpre- 

 tation 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 



