Production of Hyaline Casts by Certain Ions. 167 



which are strongly acid cause a peculiar muscular stiffness which 

 masks the central action. The alkaloid itself causes also a certain 

 muscular stiffness but it is much less marked and is only trouble- 

 some with large doses. The alkaloid was therefore used in these 

 experiments. As was the case with other convulsant drugs we 

 found the action of caffein much greater in the cold. If the frogs 

 are kept cold tetanus can be obtained with doses which are too low 

 to markedly affect the muscles. 



In contrast to morphin we found that both in the cold (2-5 0 C.) 

 and in the warm (12-18 0 C.) there was no difference between 

 normal and decerebrate frogs in their response to the convulsant 

 action of caffein. In both tetanus was obtained in the cold in all 

 frogs with doses of 0.2 mg. p. gm. and in most frogs with 0.1 mg. 

 p. gm. At room temperature tetanus was constantly obtained in 

 normal decerebrate frogs with doses of 0.6 mg. p. gm. but never 

 in either with 0.3 mg. p. gm. 



The experiments show that there is a difference of some sort 

 between the actions of caffein and morphin on the central nervous 

 system although the convulsions are identical in appearance. 



102 (919) 



On the production of hyaline casts by certain ions. 



By F. L. Gates and S. J. Meltzer. 



[From the Department of Physiology and Pharmacology of the Rocke- 

 feller Institute for Medical Research.] 



At the February meeting of this Society one of us (G.) reported 

 that after an intravenous or intramuscular injection of a sublethal 

 dose of a solution of magnesium sulphate in dogs hyaline casts 

 invariably appear in the urine. As a result of this observation a 

 series of experiments was made to answer the question as to which 

 of the ions of the injected salt is the cause of the appearance of 

 the hyaline casts — the kation magnesium, or the anion S0 4 , the 

 sulphate radical. We have tested in the first place several mag- 

 nesium salts as well as several sulphates. This led up to further 

 experimentation with some salts which contain neither magnesium 

 nor the sulphate radical. Briefly stated, our results are in general 



