ix] Iiifa-iiHilIate Precentral Arcti 225 



AURAPHIA. 



By most neurologists writing is regarded as a skilled act, to a certain extent comparable 

 with speaking, and Bastian maintains that a cheirographic centre exists as certainly as does 

 that for articulate speech, and in the corresponding hemisphere. The condition is neither so 

 common nor so clearly defined as aphasia, and accordingly an insufficiency of cases has been 

 observed to allow of a satisfactory and precise localisation of the area to which it is related; 

 still, judging from cases which have been published and from the diagrams of Bastian, Wylie, 

 and others who have made a special study of this subject, we may place the centre at the 

 base of the middle frontal gyrus, immediately above the hinder extremity of the inferior 

 frontal sulcus, and at any rate regard this part as one of particular vulnerability. 



Involving as it does the power of spontaneous writing, writing from dictation and 

 copying, this faculty, like speech, is exceedingly complex, and one in which the motor 

 component is associated with intricate psychic agencies, but again it is of the motor element 

 alone that I propose to write. 



Now to me it is a point of special interest that the supposed cheirographic centre, 

 like the centre for speech, forms a part of the " intermediate precentral " cortex, and more 

 interesting still to find that it is located exactly on a level with that part of the 

 " precentral " strip of cortex which I believe to stand in direct relation with the hand 

 muscles. (See chapter in, case of amputation of the hand.) This, I think, is an association 

 of the highest significance, but not to labour the point I will say only that much of what 

 has been written on the function of the cortex of Broca's area in its relation to the 

 so-called primary centres probably applies here, and that by means of the cells and fibres 

 in the cheirographic centre a higher control is exercised over the more direct motor elements 

 resident in the hand centre of the " precentral " area. 



But it cannot be said that writing is the only accomplishment depending on the 

 integrity of the " intermediate " cortex lying anterior to the hand area ; there are numerous 

 other skilled movements, such as knitting, sewing, type-setting, the fingering of musical 

 instruments, &c., which the hand muscles must be specially educated to perform and which 

 require the exercise of a higher volition, and in the execution of these a varying extent 

 of the "lower" field of cortex and also of that at the "higher" level, in proportion to the 

 degree in which the different muscles participate in the particular act, must be called 

 into play. 



ON HIGH AND LOW EVOLUTIONARY MOVEMENTS. 



The development of what practically amounts to a law is now seen. This law may 

 be stated as follows, in ilie " intermediate precentral " cortex there is a sequential deposition 

 of centres for the control of higher evolutionary movements, following the same order from 

 above downwards us that observed in the "precentral" area proper. There is the highest 

 probability that corresponding centres in each area are associated by commissural fibres, 

 and that corresponding centres lie approximately on the same level, and at all events in 

 juxtaposition. 



Viewed in this light the field of " intermediate " cortex lying frontal to the leg area 

 should likewise possess a higher function, and I see no reason why it should not. True 

 it is that no clinical data can be adduced which provide information regarding the effects 

 of a destructive lesion restricted to this particular stretch of cortex, but I venture to say 



C. 29 



