Editorial. 167 



any central neurones. This plasticity of the central organ, 

 then, seems to be functional largely, not merely regenerative or 

 structural. And this again will have an application in any at- 

 tempt to define the value of the neurone. 



Some progress has been made with the functional analysis 

 of the neurone. Van Gehuchten's law of the polarization of 

 the neurone (the dendrite being cellulipetal, the neurite celluli- 

 fugal), while certainly not universally applicable, is neverthe- 

 less quite generally true in higher vertebrates. The selective 

 action of certain drugs on parts of the neurone is well known. 

 Thus, curare will paralyze the terminal arborization (motor end- 

 plate) of peripheral somatic motor neurones without destroying 

 the functional integrity of the remainder of the neurone, and it 

 is probable that nicotine acts in a similar way upon the terminal 

 arborization of the pre-ganglionic sympathetic neurones. And, 

 still more recently, Langley has made it very probable that the 

 difference between vaso-constrictor nerves and vaso-dilator 

 nerves lies in the mode of the ending upon the unstriated muscle 

 cells of the arteries of the post-ganglionic sympathetic neurones 

 involved, and not upon the general character of these neurones 

 or their central connections. 



Of much greater importance is the differentiation within 

 the neurone of neurofibrils and a more fluid plasma — apparently 

 a conducting substance and its nutrient stroma. And the 

 further differentiation within the latter of Nissl bodies, we are 

 taught, is a device for the distribution of a modified nuclear 

 chromatin to facilitate rapid metabolism in the cytoplasm. 



We hear much recently about neo-vitalism in biology. In 

 the minds of some the mechanical theory of life is on the de- 

 cline. It is asserted that physics and chemistry have not ex- 

 plained organic phenomena as was anticipated by the defenders 

 of the mechanical theory fifty years ago. Many biological facts 

 are not as yet capable of satisfactory explanation in terms of 



