238 Experimental Researches on the ["^iZmai. muj^s'o*' 



II. — Physiolog ical Phenomena. 



The physiological phenomena are more marked even than the 

 anatomical observations. 



A certain number of frogs selected for these researches were 

 operated on below the reflex centre of the roots which compose the 

 sciatic plexus in a manner to destroy all spontaneous and reflex 

 mobihty in the hind limbs. Another series were operated on above 

 this centre so as to preserve the reflex mobihty.* 



In both cases, at the end of a month, we have seen the voluntary 

 movements reappear in the previously paralyzed parts, and the 

 conscient sensibility soon after exhibits itself. At the end of six 

 mouths the frogs move away spontaneously, and perceive impres- 

 sions just as they did before the operation. The portion of the 

 cord removed was about two millimetres. 



The conclusions to be drawn immediately from our researches 

 are the following : — 



1 . The spinal cord in the frog may repair the loss of substance 

 sustained in its proper tissue by the aid of a new medullary tissue. 



2. The return of the functions of the cord which had been 

 suspended by the operation coincides with the regeneration of its 

 anatomical elements. 



3. This anatomical and functional regeneration takes place 

 gradually. In the histological repair it is the cells which first 

 appear, and the fibres after. And in the case of the functional 

 repair it is voluntary motility which is first restored. 



If now we proceed to an analysis of the data furnished by our 

 researches, we are led to compare the mode of regeneration of the 

 cord with that of the brain and of the nerves. In regard to tlie 

 anatomical conditions, the reparation of the cord resembles that of 

 the brain — as Voit and Kolhnan have demonstrated it — by the new 

 formation of nerve-ceUs in the reparative tissue; but it oflfers a 

 still greater analogy with the reproduction of the nerves (as de- 

 scribed by Schwann, Vulpian, Phiiippeaux, Eobin, and Laveran), 

 because of the funicular form of the new tissue which removes the 

 " solution of continuity," and by the appearance of the two surfaces 

 of the section in the first phase of regeneration. 



As regards the physiological phenomena, the reappearance of 

 the conductibility of the cord for voluntary impressions tends to 

 assimilate the cord to a root of a spinal nerve, whilst the alterations 

 found in the two segments of the cord demonstrate that the portion 

 of the cord remaining takes up — with regard to the elements anterior 

 and posterior to the part excised — the functions of a nutritive centre. 



The metliod of regenerating the cord would therefore occupy an 



* Tliesc researches are to be found in a memoir entitled ' De la Situation et 

 de I'e'tendu des autres reflexes de la nouvelle e'piniere cliez la grenouille.' Extrait 

 des Memoircs de rAcade'mie Royale des Sciences dc Belgiqne, t. xxi. 1870. 



