lO ROYAL SOCIETY OF CANADA 



In by far the greater number of cases examined the cortical centre 

 for the hind-leg- was functionally active at a somewhat earlier date than 

 that for the fore-limb. 



The centres for movements of the head as a whole and of its various 

 parts are developed later than those for the limbs. 



In the case of large bi'oeds of dogs the cortical motor centres become 

 functionally active at a later date than in small breeds or in mongrels. 



All the principal motor centres arc functionally active within about 

 the first thirty days of life ; most of them earlier. 



Removal of those parts of the cortex producing movements when 

 elcctricall}' excited does not prevent those movements being cailsed by 

 the animal itself, such movements being executed about as well as before 

 the cortical ablation, even when that involves an area more extensive 

 than that marked out b,y stimulation. 



The medulla is functionally active in most instances somewhat earlier 

 than the cortex, but never at birth nor for several days afterwards. 



EXPERIMENTAL RESULTS. 

 11.— The Cat. 



Case J. — Kitten of 4 to S /lours.— Ether. All conditions favourable. 



Results negative as regards both cortex and medulla to any strength of 

 current. 

 Case U.— Kitten ; Ufh dai/.— Eyes closed. Ether. 



With current C, movement of fore-leg ; this is very distinct and is repeated 

 half a dozen times. The same result on the opposite side, though there is 

 considerable loss of blood on that side. Removal of cortex over the motor 

 area on the side first opened and stimulation in the same manner results in 

 movements of both fore-leg and hind-leg. 

 Case Ul.— Kitten ; 5th (]ai/.—'EyeH closed. Ether. 



With current B, on stimulating two areas adjacent to each other, move- 

 ments in the one case of the fore-leg, in the other of the hind-leg. When 

 th • electrodes are placed between these areas there is a tendency to movement 

 in both legs. The .same applies to the opposite side. 



On cutting away the cortex, get movements of both legs with best 

 localization for hind-leg. 

 Cask IV. -Kitten ; 7th r/a//.- Eyes unopened. Ether. 



With current B, get movements of fore-leg by stimulation of each side 

 of the brain ; soon leads to exhaustion; not very well localized, but is best 

 marked when a certain limited area, adjoining the crucial sulcus, and not 

 far from the middle line, is stinmlated. In this case both areas for some 

 distance around the crucial sulcus removed deeply and the wound clo.sed. 

 Cask \'. Kitten ; 7th day.—Eyea unopened. Pother. 



With strongest current get movement of the fore-leg, but no other. 

 Case Vl.— Kitten; 7th to Sth daij.— Eyes beginning to open. Ether. 

 With current B get movement of fore-leg and both hind-legs. 



Case VÏI.- Kitteyi ; Sth r/a.//.— Eyes open. Ether. 



On stimulating different brain areas with current B get the movement of 

 both the fore-leg and the hind leg, but the former responds distinctly better, and 



