226 On High and Lotv Evolutionary Movements [CHAP. 



that the question is one worthy of further research. Of course, for many reasons, the chief 

 of which is that they are constantly in use for purposes of locomotion, the number and 

 variety of skilled movements capable of execution by the muscles of the lower extremity 

 are small by comparison with those performed by the hand and arm, but we can think of 

 some, and proof that many more remain in abeyance and are capable of being developed 

 to a high pitch of perfection is afforded by the cases of individuals deprived of the use 

 of their arms at an early age ; by these " armless wonders," writing, needlework, and other 

 complex and essentially skilled acts are performed by the foot muscles without any difficulty 1 , 

 and in such cases it is surely absurd to suppose that in, for instance, writing, the 

 cheirographic centre of ordinary individuals is called into play. It is far more likely, after 

 the doctrine of Bastian, that in every normal brain the common sensory, the visuo-psychic, 

 and the audito-psychic centres, probably by means of the tapetum and the fasciculus 

 longitudinalis superior, have extensive connections with all the higher centres for muscular 

 movements, and that many associations usually not exerted may be called up in educating 

 little-used muscles to perform special skilled movements. 



If then we are correct in assuming that the cortex of the " intermediate precentral " 

 area exercises control over what in the terms of Hughlings Jackson we may call higher 

 evolutionary movements, and thus has a more or less restricted motor function, it remains 

 for us to explain the origin of movements of a lower order, movements which are perhaps 

 most suitably expressed by the term automatic, and of such those employed in progression 

 are typical examples-. And in regard to these the proposition which appears most tenable 

 is that they are dependent upon impulses arising primarily in the giant cells of Betz 

 occupying the " precentral " area proper ; but it must be admitted that direct proof on this 

 point will be long in coming, because the organisation of the motor area with reference to the 

 representation of the different groups of muscles in the various forms of movement is 

 so infinitely complex, and also because it is almost impossible in the course of experiment 

 or in nature to obtain and observe the results of a lesion so restricted anatomically as to 

 throw light on the question ; and, again, restitution of function is a stumbling-block, for 

 we know that almost invariably in the case of lower animals and occasionally in human 

 beings (cases of porencephaly), obliteration of the motor cortex, Betz cells and all, is followed 

 sooner or later by recuperation of movement. Still for one thing the condition of affairs 

 seen in cases of motor aphasia, and presumably also in agraphia, where with paralysis of 

 higher movement, primary or automatic movement of the muscles concerned is left intact, 

 is veiy significant, and seems capable of explanation on no other ground. Further we have 

 been told (Foster) that by carrying a vertical incision through the depth of the grey 

 matter, and so isolating a motor field, no alteration of stimulative effects is obtained, but 

 paralysis of movement ensues, and this has been explained by a severance of nervous 

 ties. And although this operation was performed prior to the new definition of the motor 

 area and therefore cannot be used in support of the present argument, the finding is, still, 

 of the greatest interest ; and in spite of the complicated effect of nutritive changes 

 necessarily brought about by injury to the pial blood vessels, it would be instructive to watch 

 the effect of the purer operation of isolating the Betz cells by carrying a similar incision 

 down the line of demarcation between the " precentral " and " intermediate precentral " areas. 



1 The education of the left hand by right-sided hemiplegics is on all fours with this. 



2 The movements called by Broadbent "bilaterally associated," that is, movements dependent on muscles which are 

 bilaterally excitable, such as those of the trunk, leg, larynx, and jaw, might be included in this category. 



