OX THE MAMMALIAN NERVOUS SYSTEM. 271 



CHAPTER II. HISTORICAL. 



We consider it advisable to give a brief sketch or rather catalogue of the chief 

 facts which have been ascertained concerning the specific function of nerve centres, 

 and the conductivity of nerve fibres, so far as the central nervous svstem is concerned, 

 in order that the various points we raise in the rest of the paper may be rendered 

 more intelligible when the results obtained by our method are contrasted with those 

 discovered by other means. It is naturally impossible for us to give on the present 

 occasion a complete history of this vast subject ; we would only, therefore, allude 

 to those points towards the further elucidation of which we have directed the 

 present research. The procedures employed by various authors with the exception 

 of the galvanometric method may be enumerated as follows : 



1. Electrical and other stimulation with direct observation of the phenomena 

 evoked. 



2. Stimulation with graphic record of muscular and other movements produced. 



3. The method of anatomically observing the degeneration of nerve fibres consequent 

 upon their separation from nerve centres with which they are in functional relation. 



4. The embryological method of observing the development or differentiation of 

 tracts and fibres. 



Of the foregoing methods, the first wag the one by means of which the principles 

 of localisation were earliest determined, and in this connection it is scarcely necessary 

 to do more than allude by name to HITZIG and FRITSCH, FERRIER, MUNK, LUCIANI, 

 ALBERTONI, and others. The results they obtained are to be classed with those 

 gained by means of the second method of recording muscular and other movements, 

 employed in the analysis of the functions of the central nervous system for the 

 first time by FRANCOIS FRAXCK and PITRES, and in the subsequent investigations 

 of BUBNOFF and HEIDENHAIN. They are open to the same objection, viz., that since 

 they involve motor function they necessarily exhibit the activity of two sets of central 

 mechanisms, and that therefore they only indicate the functions of the paths which 

 run in the central nervous system in so far as these functions are modified by those 

 paths being intimately connected with the lower or bulbo-spinal centres. 



The degeneration method, in which localisation of a nerve path is accomplished by 

 means of studying the retrograde changes which nerve fibres undergo when they are 

 cut off from the lowest nerve centre, with which they are in relation, should they 

 happen to be paths for ascending transmission, or vice versd from the highest nerve 

 centre for descending transmission was initiated by TtiRCK and followed up more 

 especially by CHARCOT and his pupils, as well as by a large number of investigators, 

 and neuro-pathologists of all countries. This method is not free from possible 

 error, since in the case of nerve channels connected at each end with central 

 structures, we do not yet know what the nature of the connection must be which 

 enables the nerve channel to successfullv resist degeneration. Therefore, while the 



