034 



prepared macroscopicallv, to one intercostal resp. to one lumbar 

 nerve, unisegmental or pluri-segmental nerve-canals. For whilst it 

 is admitted almost generally that the intercostal nerves are uniseg- 

 mental courses, Eislkr ') believes he has sufficient grounds for 

 stating that delicate nerve-plexus, situated on the inside of the ribs 

 always connect two intercostal nerves. This being so, an interchange 

 would occur here between nerve-fibres of a different segmental origin. 

 Concerning the nerve-distribation of the root-areas, this question 

 may be formulated as follows: Do the nerve-fibres of each separate 

 dorsal root of the spinal cord reach the skin-area belonging to that 

 root along one single dorsal lateral or ventral pei-forating nerve- 

 trunk, or along several ones? 



In order to solve this question, I made the following experiment. 

 After the afore mentioned method of Shkrkin(jton, the dorsal (and 

 ventral) spinal nerve root of a segment on one side of the spinal cord 

 of some dogs was "isolated", usually between three cranial and as 

 many caudal roots, which were cut (hrough extradural. This being done, 

 the isolated root-area, corresponding to the isolated root, was 

 demarcated against the two insensible zones, corresponding to the 

 sectioned roots. Situation, form and extension of the sensible root- 

 area once being well defined, the skin was entirely cleft both in the 

 cranial and in the caudal insensible zone by a slit passing from 

 the mid-dorsal to the mid-ventral line. This of course could be done 

 without narcosis. Immediately after this, a search was made for 

 the perforating skin-nerves, and at least three successive ones of 

 these in cranio-caudal direction, in the dorsal, lateral, and ventral 

 skin-area, were prepared free, as much as possible avoiding any 

 lesion of them. Next lo this, by means of the induction-current, 

 these nerves were stimulated to ascertain whether they conducted 

 painstimuli. Invariably the result was, that for each skin-area such 

 was only the case with these bi-anches that belonged to one point 

 of entrance. Irritation of the oiher branches, even with the strongest 

 induction currents (the bobbin being enrirely pushed in), never 

 produced any symptom of pain, if slippings of the current were 

 avoided. This result was wholly confirmed by a contra-experiment. 

 If, after careful determination of the dorsal, lateral and eventually 

 ventral branches, which were conductors of pain-stimuli, these branches 

 were cut through, the sensibility in the isolated root-area proved to 

 be destroyed entirely and irrevocably. 



1) P. EisLER. Ueber die Ursaclien dei' Gefleclithildiing an den periplieren Nerven. 

 Verb, d Anatom. Gesellsch a. d. iGe Vers, in Halle. 1!)02. S. 200. 



