of Movements in the Lumbar Region of the Spinal Cord. 245 



Operative Procedure. 



Exposure of spinal cord. 



Division of cord and isolation of segments. 



The cord was exposed with due observation of well-known precau- 

 tions (Gotch and Horsley, ' Phil. Trans.,' vol. 182, B, 1891). In some 

 cases the spinal cord and roots were stimulated at first in continuity. 

 In others, before proceeding to experiment, the spinal cord was 

 completely divided at from two to eight segments above the part 

 experimented upon. The spinal roots were divided as detailed in the 

 paper. 



METHOD OP EXCITATION. 

 I. Electrical. 



Apparatus. A single Daniell cell was used which supplied a Du 

 Bois Beymond's inductorinm of the usual type, the secondary coil 

 being 20 cm. or more from the primary. The electrodes attached to 

 the secondary coil consisted of closely approximated (1 mm.) plati- 

 num points. The duration of excitation was, as a rule, momentary, 

 and never exceeded 1 2 seconds. 



(a) Excitation of Nerve Roots. The nerve roots were raised in the 

 air and the electrodes usually applied, so that the direction of the 

 exciting current was transverse to the nerve fibres. 



(6) Excitation of the Spinal Cord. The surface of the cord was 

 gently dabbed with small wool swabs, kept in warm saline solution 

 and squeezed dry, before the electrodes were applied. The duration 

 of excitation was always brief, rarely exceeding one second. 



The value of the method may be estimated by considering the 

 following facts. On stimulation of the surface of the spinal cord as 

 already mentioned, movement was always elicited in the leg on the 

 side stimulated, when the electrode was applied to the surface of the 

 posterior column, but never, as far as I was able to see, could move- 

 ment be obtained by the application of this strength or even con- 

 siderably greater strength of stimulus to the lateral or anterior 

 columns, when adequate precautions (vide paper) were taken to 

 prevent the direct spread of the current to the neighbouring root 

 fibres. The movement elicited from stimulating the posterior 

 columns was always marked and quite definite, and merely depended 

 in intensity upon the conditions stated below. For instance, apply- 

 ing the electrodes to the surface of the postero-external column in 

 the fifth lumbar segment of the dog on the left side produced lateral 

 flexion of the spinal column to the same side, flexion and adduction of 

 the hip, flexion of the knee and toes, and movement in the tail 

 (flexion to the same side). But the chief result was the very local 

 effect which could be obtained by varying the point stimulated j thus, 



