MOTOR FUNCTIONS OF CEREBRAL CORTEX OF CAT 183 



perienced in exposing the anterior areas without considerable 

 shock and hemorrhage, and in other animals the first trephine 

 opening was made in the glabellar region, as far forwards as 

 possible, without taking in the orbital margins. This exposed 

 the upper portions of the two frontal bony sinuses. A second 

 opening was then made in the median line sufficiently posterior 

 to clear the posterior wall of the sinuses. The button, when re- 

 moved, did not tear the vascular sinus, but considerable bleed- 

 ing from the bone and small vessels followed. This was usually 

 stopped with hot sponges and, if much blood appeared to be 

 lost, the animal was given from 5 to 15 cc. of salt solution sub- 

 cutaneously. The openings were enlarged with bone forceps on 

 all sides and the plate of bone between the frontal bony sinuses 

 and the brain cavity was removed. After all hemorrhage had 

 been stopped, by means of hot sponges and bone wax, and the 

 animal had rested a few minutes, the dura was slit and laid back, 

 thus exposing the cerebral surface of one side. The brain tissue 

 was kept moist and warm by frequent applications of cotton 

 sponges, wet in warm salt solution. Bipolar stimulation was 

 used in most experiments, monopolar in a few. The former 

 method was found most convenient. 



Stimulation was applied from an inductorium by means of 

 platinum electrodes with the center of the points about 1.5 mm. 

 apart. The secondary coil was kept at such a distance from the 

 primary that the stimuli were supraminimal, but not maximal. 

 After twenty or thirty tests, each stimulus being approximately 

 two seconds in length, at intervals of one or two minutes, the 

 brain was covered with warm, moist sponges and allowed to rest 

 for a quarter of an hour. 



The use of methods for keeping the body temperature at a 

 normal line was found necessary. For this purpose the animal 

 was kept throughout the tests on a metal box containing a 

 lighted electric lamp, and when observations of reactions were 

 not being made the animal was covered with cloths. 



