244 Dr. C. S. Sherrington. Double (Anticlrome) 



The reaction is obtainable when the transection has been made 

 altogether below the nuclei graciles et cuneati. It therefore does not 

 necessarily involve the cells of those nuclei. 



The reaction is not prevented by complete bilateral transverse 

 severance of the ventro- lateral columns and grey matter of the cord 

 at the — 



5th cervical root level, 

 nor at the 8th ,, ,, 

 „ 5th thoracic „ 

 „ 1st lumbar „ 

 „ 5th „ „ (cat). 



The reaction is at once annulled on severance of the dorsal columns 

 at any one of the above levels, although at the same time the ventro- 

 lateral columns and the grey matter remain intact. 



The reaction from the left /. gracilis is annulled by severance of 

 the left dorsal column, that of the right by the severance of the 

 right. 



The reaction can almost always be obtained — although incom- 

 pletely — by mechanical excitation, e.g., by compression with ivory 

 forceps, often even by a mere touching with the forceps. 



That the conduction involved in the reaction does not implicate 

 the fibres of the pyramidal tract — which at first instance sug- 

 gest themselves as a source of fallacy — seems clear in light of the 

 above. That supposition is also, and I think finally, excluded by 

 the following observation. I have found the " long intra-spinal 

 reflexes," like sub-cerebral rigiditjr (" decerebrate tonus,"*) locally 

 abolished, or greatly depressed by total severance of the sensory 

 spinal roots belonging to their own region of terminal discharge. 

 Thus, to take an instance given in my former paper, if the right 

 forepaw be stimulated the paths of "short spinal conduction"* 

 from it lead to discharge of its own flexors of elbow, extensors of 

 wrist, &c, as specified in the paper ; and the paths of " long spinal 

 conduction " from it lead to discharge of the muscles of the idiolateral 

 hind limb. To evoke from the forepaw movement of the contra- 

 lateral hind limb is relatively difficult ; this contralateral movement 

 is less commonlv and less easily obtained, and when obtained less 

 vigorous, less prolonged, and usually commences later than the 

 idiolateral. But if, in the instance taken, the series of afferent 

 spinal roots belonging to the right hind limb be severed, and stimu- 

 lation of the forepaw (right) be then repeated, the movement 

 induced in the hind limbs is contralateral, i.e., a crossed one. In the 



* " Experiments in examination of the Peripheral Distribution of the Fibres of 

 the Posterior Roots of some Spinal Nerves, Part II," Abstract, 'Roy. Soc. Proc./ 

 vol. 60, No. 365. 



