THE KANSAS UNIVERSITY 

 SCIENCE BULLETIN. 



Vol. V, No. 3] OCTOBER, 1909. ['^"^xvf nTs 



THE INFLUENCE OF MAGNESIUM SULPHATE ON THE 

 MOTOR CELLS OF THE CEREBRAL CORTEX. 



BY H. F. HYNDMAN AND W. E. MICHENER. 

 (Contribution from the Physiological Laboratory of the University of Kansas.) 



'T^'^HE experiments of which the results are here briefly re- 

 ^ corded were undertaken for the purpose of ascertaining 

 whether magnesium sulphate paralyzed the motor cells of the 

 cerebral cortex. It was found that 1.5 grams of magnesium 

 sulphate per kilo, when injected in rabbits subcutaneously, pro- 

 duced anaesthesia in about fifty minutes that lasted two hours. 



Rabbits were employed in all of the tests and three series of 

 experiments were carried out. 



In the first set ether was given, and when anaesthesia had 

 developed the motor areas were exposed, and a definite, well- 

 defined small area, which when stimulated with insulated 

 platinum electrodes with a determined minimal strength of 

 induced current, caused the hind leg of the side opposite to the 

 one stimulated to give a definite contraction. The cortex was 

 then carefully removed and again the minimal strength of cur- 

 rent determined that would produce the same extent of con- 

 traction as before in the same leg. The animal was then 

 allowed to come from under the influence of ether, and then an 

 anaesthetic dose of magnesium sulphate was injected. The 

 same area on the opposite side was now stimulated with a de- 

 termined minimal strength of current that would produce the 

 same extent of contraction as was secured with ether. The 

 cortex was then removed and again the minimal strength of 

 current determined. 



The experiment was also modified in that the minimal 



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