CHAPTER XXX. 



NEUROLOGICAL METHODS INTRODUCTION AND SECTION 



METHODS. 



680. Introduction. Histological research into the structure 

 of the nervous system pursues two ends. Either it is desired 

 to elucidate the minute structure of the nervous elements or 

 neurons (neurites FISH), that is to say, the internal organisa- 

 tion of nerve cells and nerve fibres : the processes employed 

 to this end forming a group of cytological methods. Or it is 

 desired to study the form of nerve cells, the exact distribution 

 of the divers groups of nerve cells in the grey matter, the 

 connections that are formed by means of nerve fibres between 

 these groups of nerve cells or " nuclei," and to follow out the 

 intricate course of the tracts of fibres that enter into the 

 constitution of the white matter of the cerebro-spinal axis. 

 The processes employed in all these researches form a group 

 of the anatomical methods of neurology. It is more espe- 

 cially in this group that we find highly special methods of 

 selective coloration. This group may be divided as follows : 



A. Nerve Fibre*. 



(a) Myelin stains ; comprising the methods of WKIGERT, 

 and similar methods. 



(fe) Axis-cylinder stains, and axis-cylinder and myeliii 

 stains. 



B. Nerve Cells. 



(c) Axis-cylinder-and- protoplasm stains, comprising the 

 methylen blue method and some rather old-fashioned general 

 stains. 



