86 



Scientific Proceedings (28). 



We shall give here no details, but state the results in the 

 briefest possible way. 



The average quantity of each salt per kilo which caused death, 

 was as follows: MgCl 2 , 2.35 ex.; CaCl 2 , 4 c.c; KC1, 6.23 c.c, 

 and NaCl, 63.24 c.c. These figures refer to the crystalline salts 

 when dissolved in molecular solution. When, however, these 

 values are reduced to that of the anhydrous salts, the figures read 

 as follows : The fatal dose of magnesium chloride is 0.223 gram 

 per kilo (dog); of calcium chloride it is 0.444; °f potassium 

 chloride 0.464; and sodium chloride is fatal only when 3.7 grams 

 of the salt are given per kilo. In other words, magnesium chloride 

 is twice as toxic as calcium chloride or potassium chloride. 

 Again, potassium chloride is about eight times more toxic than 

 sodium chloride. In the case of the latter we have to remember 

 that the solution ran in twice as rapidly as the solutions of the 

 other salts, which means that the comparative toxicity of sodium 

 chloride is even much less than appears in the above scale. 



49 (305) 



The action of calcium upon the pupil and its relation to the 

 effects of mydriatics. 



By JOHN AUER and S. J. MELTZER. 



\From the Department of Physiology and Pharmacology of the 

 Rockefeller Institute for Medical Research.'] 



The intravenous injection of calcium exerts a pronounced effect 

 upon the mechanism of pupilary constriction. The solution em- 

 ployed was m/8 CaCl 2 ; this was injected slowly through the ex- 

 ternal jugular vein of rabbits ; in some instances the ear veins were 

 used. After 12 to 14 c.c. of the solution had run in, stimulation 

 of the cervical sympathetic nerves no longer caused dilatation of 

 the pupil. At the same time, the pupil appeared to be smaller 

 than normal and reacted less readily to light. When 20 to 25 

 c.c. had entered, the pupils, as a rule, became almost pinpoint in 

 size. If the infusion was now stopped, the pupils remained con- 

 tracted for about thirty minutes, and usually about two hours 

 elapsed before the pupils again reached their normal size. There 



