198 Ley ton and Sherrington 



catchinof hold of the bars with it, not so much due to the dig-its as to the 

 ankle. The right foot, as the animal climbed about, sometimes missed the 

 bars. It never grasped the bar so fully as did left. The limb was, how- 

 ever, freely moved and used. Next day the animal was lively, and fed 

 well ; the clumsiness and want of strength in climbing with right leg was 

 distinctly less than on the day previous. 



May 24. — The right leg is now well used, although obviously some- 

 what clumsy. Wound has healed almost. Animal has no difficulty in 

 supporting itself with right leg. 



May 30. — Very little obvious impairment of movements of right leg. 



June 3. — Left hemisphere exposed in centralis region under deep 

 ana3sthesia. The whole of free faces of precentral and post-central gyri 

 explored with faradisation. The cortex of leg area below the lesion 

 yielded no hip or leg movement, but only movements of abdominal wall 

 and trunk. 



The extreme mesial ed^e and the whole mesial face of the leg area 

 were then explored and the motor responses mapped (hg. 24). Animal 

 then killed with chloroform. 



Examination of the bulb and spinal cord by the Marchi method revealed 

 (fig. 25) a heavy degeneration scattered throughout the left pyramid, but 

 confined to that. At Lst cervical segment there is a heavy scattered 

 degeneration in the right lateral colunni occupying the pyramidal tract 

 area as usually figured, but also occupying a considerable length of dorsal 

 half of the margin of the column ; this marginal degeneration is separated 

 from the deeper area of degeneration by a dorso-ventral strip containing 

 large sound fibres (cerebellar tract), but the marginal and deep areas conjoin, 

 especially ventrally, by thinly scattered intervening degeneration. In the 

 other (ipsilateral lateral) column a small amount of diffuse degeneration 

 extends through the pyramidal tract area. In the ipsilateral ventral 

 column, beside the whole length of the lip of the ventral fissure, a ventral 

 direct pyramidal degeneration exists. A couple of segments lower the 

 degeneration in contralateral lateral column has assumed a different shape, 

 the marginal degeneration lying farther ventral, and joined by a narrow 

 isthmus dorsally to the main deep-lying degenerate area. Ipsilateral 

 uncrossed pyramidal tract degeneration in lateral column is still obvious, 

 so also the uncrossed ventral, but latter lies deeper down the lip of ventral 

 fissure. In the lower cervical region the contralateral degeneration has 

 assumed an oval form, with a long ventral extension reaching ventral 

 margin of lateral column. In the ipsilateral side, lateral and ventral 

 columns exhibit the lateral and ventral uncrossed pyramidal degenera- 

 tions as before. In upper thoracic and in mid-thoracic levels the contra- 

 lateral degeneration is marked by the considerable extent of its ventral 

 sweep, and the ipsilateral by the gradual shift of the ventral column 

 portion of it so as to lie in the ventral portion of the ventral fissure's lip 

 once more. There has been no marked, or indeed obvious, decrease in 



