26 KANSAS UNIVERSITY SCIENCE BULLETIN. 



strength of current for contraction was determined after cortex 

 stimulation, and then, when the animal recovered from the 

 ether effect, magnesium sulphate anaesthesia was secured. 

 Again the cortex was stimulated with a minimal strength of 

 induced current. 



The results of this set of experiments were that it required 

 exactly the same strength of current to produce the same extent 

 of contractions, both with the cortex intact as well as when the 

 motor cells were removed and the fibers directly stimulated 

 under ether as under magnesium sulphate anaesthesia. In each 

 case the strength of current required for the same contraction 

 was greater when the motor fibers were directly stimulated 

 after the motor cells were removed than when the contractions 

 were secured indirectly by direct stimulation of the motor cells. 



The second set of experiments differed from the first set in 

 that the same procedure was carried out under magnesium 

 sulphate anaesthesia alone. 



The third set of experiments consisted in determining the 

 strength of current when applied to the central ends of the 

 eighth and seventh cervical dorsal spinal nerves under ether 

 and magnesium sulphate anaesthesia that would reflexly cause 

 contraction of certain muscles of the mouth. 



A comparison of all the experiments showed that the same 

 minimal strength of current was required to produce the same 

 extent of contraction under ether as under magnesium sulphate 

 anaesthesia, whether applied directly to the motor fibers, indi- 

 rectly to the fibers through the motor cortical cells, or when 

 applied to afferent fibers that secured a reflex response; and 

 that a greater strength of current was required when applied 

 directly to the motor fibers than when the impulses reached 

 these through stimulation of the motor cortical cells. 



We conclude, therefore, that magnesium sulphate anaesthesia 

 does not paralyze the motor cells of the cerebral cortex in the 

 rabbit. 



We take this opportunity to thank Doctor Hyde, under whose 

 supervision these experiments were conducted, for her many 

 kind suggestions. 



