3'8 BULLETIN OF THE LABDRATOKIKS 



furnished the sections most frequently described and figured beyond. 

 Ether was employed as an anesthetic, and the skin was parted down 

 the median line of the head and the skull removed over the anterior 

 and middle parts of the left hemisphere. The current used was from 

 one Grove cell and was just enough to operate the induction-coil, pro- 

 ducing an irritation easily endured by the tongue When the elec- 

 trodes were introduced at a, Fi^. 4, Plate V, (at about the anterior 

 one-third, near the median line and corresponding approximately to 

 Munk's region C of the dog) a forward and outward motion of the 

 right fore leg was produced. A stronger current produced an electro- 

 tonic contraction of the muscles of the whole right side. At the point 

 b^ about 5 mm. behind and a little outward from the above (corres- 

 ponding to about the posterior margin of Munk's region U), the stim- 

 ulus produced a straightening of the right hind leg. At the point ^, 

 about 8 mm. behind h, and near the median fissure (corresponding to 

 about Munk's region F, near the median line), the stimulation resulted 

 in a sharp contraction of the orbicularis palpebrarum and orbicularis 

 oris of the right side and some feeble contraction of the facial muscles 

 of the left side, probably due to superficial irradiation. 



At the point d, about 8 mm. behind c, and farther from the me- 

 dian fissure, (corresponding to the anterior margin of Munk's region 

 A,) the insertion of the electrodes produces no motor disturbances nor 

 did any jjoint back of d. By a series of trials it was found that the 

 electrodes produced some motor disturbance of the fore leg at all 

 points within the area marked A, but not beyond it. 



The area B likewise marks about the limits of the hind leg region. 

 An area of about 5 sq. mm. was then removed from the cortex of the left 

 side in the fore leg region at about a. The wound was then dressed and 

 the animal allowed to recover. The power of abduction of the right fore 

 leg was lost. After some time another ])ortion of the cortex was re- 

 moved, a little back of d, on the left side. After recovery it was found 

 that the animal was blind in the right eye. These experiments serve 

 to locate some of the motor and sensory regions of the cerebral cortex 

 for the subsetpient histological works. 



It may be of interest to note also one of the series of experiments 

 of electrical stimulation upon the Raccoon, Procyon lotor, which has 

 been employed for comparative study. The animal was a male about 

 three-fourths grown. Just enough current was used to drive the coil. 

 Ether and chloroform mixed were the anesthetics employed. 



