MOTOR FUNCTIONS OF CEREBRAL CORTEX OF CAT 



221 



moved was sufficiently thick to include the roof of the lateral 

 ventricle. This method of approach was adopted in order to 

 secure as complete an exposure of the corpus callosum and 

 corona radiata as possible. By such an approach the corpus 

 callosum was severed antero-posteriorly throughout its whole 

 extent. , The portion of the corona radiata laid bare included 

 most of the tissue underlying the motor cortex and a large part 

 of that underlying the extra-motor regions of the superior and 

 lateral portions of the hemisphere. 



The tests of irritability were carried out as soon as the hemor- 

 rhage, which was sometimes considerable, was arrested by pack- 

 ing lightly with surgical gauze. The same method of recording 



TABLE 8 



Results of stimulation of corpus callosum. General distribution of stimulable 

 areas, the portions of the corpus callosum in the table being related to the move- 

 ments mentioned 



results was used as in the tests of irritability of the surface. 

 It may be said that most of the animals used for the investiga- 

 tions of the irritability of the corpus callosum and corona radi- 

 ata were first used for a short time for the investigation of the 

 surface irritability. The first stimulations applied to the ex- 

 posed tissue of the corpus callosum were by means of a very weak 

 current, which was gradually increased to an amount just 

 sufficient to produce reaction, an effort being made to use as 

 weak a current as possible to prevent unnecessary fatigue of the 

 tissue. 



The accompanying table (table 8) presents the summary of 

 the results from the stimulation of the various portions of the 

 corpus callosum and table 9 gives the summary of results ob- 



