1902.] Descending Sinned Tracts in the Mammalian Corel. 115 



t: Note upon Descending Intrinsic Spinal Tracts in the Mammalian 

 Cord." By C. S. Sherrington, M.A., M.D., F.E.S., and E. E. 

 Laslett, M.D. Vict. Eeceived November 5, — Read Novem- 

 ber 27, 1902. 



In the course of experiments upon the paths of nervous conduction 

 in the spinal cord of the mammal, one of us observed* very numerous 1 

 and wide departures from the fourth so-called " law " of Pfliiger. 

 That " law " states that " Reflex-irradiation in dem Ruckenmarke 

 nach Oben, resp. Vorn, gerichtet ist ; also gegen die Medulla oblon- 

 gata."! The observation of the above-mentioned exceptions rendered 

 desirable a search for more detailed evidence of intrinsic spinal paths 

 running in the aboral direction. We therefore set about inquiring into 

 the existence of spinal paths connecting the activity of segments 

 situate nearer the head with segments lying further from the head. 

 Such evidence is obtainable with some experimental difficulty, but it 

 has been eventually forthcoming, and amounts to demonstration of the 

 microscopic course of the channels involved. It is some main features 

 of these latter that we desire to record in the present communication. 



Method. 



The method employed has been that of the Wallerian nerve-fibre 

 degeneration, but with a novel feature in the mode of application of 

 the method. For the purpose in view the ordinary establishment of a 

 cross-lesion in the spinal cord is futile. The secondary degeneration 

 then produced befalls, in the spinal region under investigation, all 

 nerve-fibres having their perikarya headward of the cross-lesion, 

 whether those perikarya lie in the cerebral hemisphere, basal ganglia, 

 mid-brain, cerebellum, bulb, or cord itself. It is obviously then 

 impossible to identify which particular ones, if any, of the degenerate 

 nerve-fibres are coming from the cord-segments whose nerve-tracts 

 are the special object of inquiry. To obviate this difficulty, we have 

 adopted a method which may be termed a method of " successive 

 deejeneration." The method consists in producing two or more succes- 

 sive degenerations with allowance of a considerable interval of time 

 between them. In the piece of cord to be examined, a first degenera- 

 tion is allowed time enough to remove all the tracts descending from 

 sources other than those the immediate object of inquiry. This is a 

 procedure which requires in our material, at shortest, 9 or 10 months 

 to complete. When the time is complete, the cord is left, as it were, 



* " Croonian Lecture," ' Phil. Trans.,' B, 1897. 



f 'Die sensoriscben Fuuctionen des Riickenmarks der Wirbelthiere, nebst einer 

 neuen Lehre iiber die Leitungsgesetze der Reflexionen ' (p. 73), Berlin, 1853. 



K 2 



