1894.] Cord following Lesion of the Cortex Cerebri. 209 



motor cortex was selected as detailed below, the selection being con- 

 firmed in each case by electrical stimulation. A small piece of the 

 cortex, about 0*4 cm. square, constituting the focus of the movement 

 observed, was removed, care being taken to remove also a little of 

 the underlying corona radiata to be sure that no cortex was left. 

 The wounds healed, without exception, within 24 hours by first 

 intention. Beyond slight paresis, which generally disappeared in 

 24 hours, no symptoms were observed to result from the excision. 

 Professor Horsley kindly did the operations for me. After three 

 weeks the animals were killed, the brain and cord hardened in 

 Miiller's solution, and stained in osmic acid after the method of 

 Marchi. 



Results of Investigations. 



Three foci of representation were selected for excision, the left 

 hemisphere being chosen in every case (vide Method of Investiga- 

 tion). 



I. Focus for the movements of the thumb. 

 II. Focus for the movements of the hallux. 



The course taken by the descending degenerated fibres was as 

 follows : 



I. Hallux Focus removed. In this case the lesion consisted of the 

 removal of about 16 sq. mm. of cortex between the superior pre- 

 central sulcus and the fissure of Rolando, and bounded below by 

 the level of the superior frontal sulcus. 



Degenerated fibres were found in both lateral columns of the 

 cord, the large majority being on the right side. The degenerated 

 fibres were scattered throughout the entire area of the crossed or 

 lateral pyramidal tract, not being restricted to any special part of it, 

 though it might be said they were a little more dense posteriorly. 

 Throughout the cervical, dorsal, and lumbar regions the total number 

 of degenerated fibres was not diminished, though, of course, relatively 

 increased in the lower cord. In the pons and medulla the degenera- 

 tion was entirely confined to the left pyramidal tract (the side of the 

 lesion). At the decussation in the upper cervical region the 

 degenerated tract divided; about one-third going to the lateral 

 column of the same side, the remaining two-thirds crossing to the 

 lateral tract on the opposite side, In the upper cervical region there 

 were a very few degenerated fibres remaining in the direct tract 

 (anterior column), and below the middle of the cervical enlargement 

 none could be seen. 



II. Thumb Focus removed. In this case the lesion consisted of a 

 similar removal of cortex at a poirt just above the lower end of the 

 intra-parietal sulcus, and between it and the fissure of Rolando, and, 

 consequently, just behind the inferior genu of the fissure of Rolando 



Q 2 



