188 Ley ton and Sherrington 



mid-line. Main blood-vessels marked in the map of the former operation 

 were re-found above and in front of the scar, and were unaltered from their 

 previous appearance. Faradisation of the cortex along the lower edge of 

 the old lesion evoked no movement in hand, but retraction and raising of 

 right angle of mouth, and at one point quite regularly a brisk turning of 

 neck and head toward the opposite side. Faradisation by plunging the 

 unipolar electrode into the soft scar, even when the penetration amounted 

 to 1 cm., failed to evoke movement. Precentral gyrus above the lesion was 

 explored up to the upper genu ; it gave the same results as at the previous 

 examination two months before. Post-central gyrus was also re-explored, 

 and no movement could be elicited by currents of even greater intensity 

 than those sufficing to evoke response from the uninjured parts of pre- 

 centralis. The old scar was then entirely cut away, and the old lesion 

 deepened everywhere by further ablation ; and the old lesion was increased 

 upward by removing part of the gyrus previously uninjured as far as the 

 line marked 3. iii. in the map (see fig. 5, A). 



On recovering from the operation narcosis the animal showed no 

 distinct aggravation of any paresis there might have been remaining in the 

 rio-ht arm. The hand was at once used well to grip the bars of its cage. 

 The animal often hung suspended by the right hand and arm ; and this 

 was the better demonstrated, because the animal seemed excited, and was 

 for a few hours particularly active. Small objects, e.g. bits of grape and 

 such as had been previously used for testing, were picked up well, and to 

 all appeai-ance as well and readily as the day before the second operation. 

 Sometimes the right arm seemed to be used not quite so freely or well as 

 before this second operation, but the difference, if really existent, was a very 

 slio-ht one. There was no obvious evidence of astereognosis. There was 

 no obvious paresis at elbow or shoulder, and no trace of paresis of face or 

 leo-. Next day, the animal doing very well and being very active, the 

 movements of right arm were thoroughly examined. No difference was 

 detected between its existing motility and that obtaining before the last 

 operation. Thumb was well and accurtitely adducted and abducted; index 

 was similarly well flexed and extended ; and both were used quite success- 

 fully to all appearance. On March 5th, forty-eight hours after the second 

 operation, the animal was seen using the tip of the right index finger, 

 the finger being isolatedly extended, for picking its teeth. Certainly no 

 recrudescence of paresis in the right arm was observable. 



April 1. — The wound has been completely healed for some time. No 

 recrudescence of paresis has at any time ensued in result of the operation 

 of March 3rd. The tendency to contracture noted shortly before the second 

 operation has become more pronounced. The arm tends to be kept 

 partially flexed at elbow, and there is some postural over-extension at 

 metacarpo-phalangeal joints, with some flexion at the phalangeal joints of 

 all the digits except thumb. 



3rd Operation, April 2. — The left hemisphere had been the field for 



