[mills] cortical cerebral LOCALIZATION 31 



In the case of all these animals it has been clearly demonstrated that 

 all motor centres are not functional equivalents — some respond more 

 readily and produce better defined movements than others. They seem 

 to be better organized. 



There appears to be all degrees of this functional variation down to 

 zero. The rabbit is an especially good illustration of some phases of this 

 principle. 



The cortical localization mapped out by Terrier for the dog, cat, 

 rabbit, cavy and rat is in the main confirmed by the jDresent investigator, 

 but considerable allowance must be made for individual differences, and 

 it is important, as has been just pointed out, to recognize that all motor 

 centres in the same animal are not functionally equivalent in the sense 

 explained above. 



The removal of motor centres in the animals made the subject of 

 this investigation does not lead to complete loss of the corresponding 

 movements, and in some cases the difference between the intact animal 

 and that operated on is, after a few" days, relatively slight ; so that it is 

 plain that motor centres in such animals are not strictly comparable with 

 motor centres in the Primates. In other words, here again the question 

 of degree of localization and functional organization (among others) 

 must be considered. 



The bird is on a wholly different plane. N"one of the ordinarily 

 recognized movements on stimulation of the cerebral cortex can be 

 excited in the bird. On the other hand, certain eye movements, both 

 intrinsic and extrinsic, follow as a result of stimulation of the cortex. 



