MOTOR FUNCTIONS OF CEREBRAL CORTEX OF CAT 219 



to the extra space or to more synaptic connections which are 

 traversed is not sure, but the great differences would rather in- 

 dicate the latter condition. One other matter should be briefly 

 considered, viz., the probability that the subcortical tissue may 

 have become more excitable than the cortical, on account of the 

 injury with its resultant loss of blood and washing with normal 

 salt solution. This is a possible explanation for such results, 

 but this explanation is not certainly warranted in view of the 

 similarities in irritability, as measured by current strength 

 necessary to produce a reaction, which were obtained. It should 

 be noted that the subcortical stimuli were given always after the 

 cortical (a condition imposed by the nature of the experiment) 

 and the stimuli, if a fatigue effect for the first tests was present, 

 should have resulted in a longer latent period for the subcortical 

 stimuli. The time of the latent period for subcortical stimuli, 

 even in view of a possible retarding fatigue effect, was shorter 

 and this is a further indication that this is not a casual result. 

 A comparison of the latencies for the corresponding cerebral 

 points, cortical and subcortical, is also instructive with respect 

 to the differences. In a few cases the subcortical latencies were 

 greater than the corresponding cortical, but not frequently. 



One further qualification should be made with respect to the 

 method and results. Although an effort was made to stimulate 

 the subcortical tissue immediately below a certain cortical point 

 which was selected, it was (and is) impossible to be certain that 

 this was accurately done. Assuming, however, that the tissue 

 immediately below the cortex was stimulated, it is not possible 

 to say that the fibers for the same overlying cells were stimu- 

 lated. One fact is, however, especially noteworthy. This is 

 that the subcortical stimulation, as a rule, resulted in a move- 

 ment of the same muscles as those from the cortical stimulation. 



It was noted that in many cases there is considerable after- 

 movement following the discontinuance of the stimulation. This 

 is true both for cortical and subcortical stimulation. Such a 

 result for subcortical stimulation is rather surprising in view of 

 the statement of Frangois-Franck that stimulation of the corona 

 radiata results in motor reactions which cease immediately after 



