28 ROYAL SOCIETY OF CANADA 



the dog and the cut : in fact, that they may be induced about as soon 

 as those for the fore-limb. 



To my mind it is perfectly clear that it cannot be maintained that 

 the movements for the hind-limb are in the same relation to the cortex in 

 the rabbit as are those for the fore-limb and the face. Whether the 

 centre exists, but is too ill-oi'ganized to be susceptible to stimulation by 

 our rough experimental methods, whether it is too readily disordered by 

 operative procedure to allow of experimental determination I do not 

 know, but I am satisfied that to represent such a centre as of the same 

 kind and demonstrable in the same way as others in the rabbit is a mis- 

 take. In some respects it would remove diflticulties if such a centre could 

 be demonstrated to exist, but on the other hand it must be borne in mind 

 that the method of locomotion in the rabbit is peculiar and is not com- 

 parable to that of the rat, cavy (guinea-pig), etc. 



As regards the cavy and the white rat I can contirm in general 

 Ferrier's localization. 1 have also examined the brown rat and the 

 mouse and tind that their cortical centres cori*espond in the main with 

 those of the white rat and the cavy. 



I have made a sufficient number of experiments on mature cats 

 and dogs to enable me to confirm in a general way the usually accepted 

 localization. 1 wish, however, to point out that there is a certain degree 

 of individuality as regards the exact position of the centres in the dog 

 and the cat, and perhaps still more in the readiness with which they may 

 be excited by electrical stimuhition. The same may be said as to the 

 effects of ablation. 



In regard to the latter, I do not find :iny functional defect of a kind 

 that prevents the animal walking within a very short time after oper- 

 ation. There is, however, a change in the animal's movements — some- 

 times at first a tendency in dogs and cats in the fore-limb to bend under 

 and for both the fore and the hind limbs to sli]) and to scrape on the 

 surface over whicli the creature walks. The latter was especially notice- 

 able in cats from which the motor areas around the crucial sulcus on 

 both .sides were completely removed by one operation. Nevertheless, 

 even in such cases, the animals rapidly improved. Soltmann's ' explan- 

 ation — loss of muscular sense — in my opinion, goes a long way to explain 

 this, though I would not deny that there is also some loss of muscular 

 power. 



In rabbits and other rodents the localization is less definite than in 

 the dog and the cat, and it seems to me a mistake to omit to state this in 

 any work on cortical localization. In raj experience the centres are not 

 nearl}' so definitely marked off and are more variable in exact position. 

 Certain movements, however, just as constantly and readily follow on 



1 .Jahr. f. Kinderlieilkunde u. Phys. I'^rzicliunji, lH7(i. 



