IX. 



NEKVE-TISSUEJ 



NERVE-TISSUE is composed of living matter, seen either as 

 an extremely delicate reticulum, or as apparently homo- 

 geneous filaments the axis-cylinders. The reticulum is of a 

 uniform width, without well-marked points of intersection (see 

 page 128, Figs. 42 and 43), as seen in the gray substance of the 

 brain and the spinal cord. In the reticular bioplasson, formations 

 are imbedded, which bear resemblance to nuclei, with distinct 

 walls and larger branching bodies, usually nucleated and reticu- 

 lar in structure viz.: the ganglionic elements. From the retic- 

 ulum of the gray substance, and also from that of ganglionic 

 elements, somewhat thicker filaments emanate, the axis-cylin- 

 ders, which are the essential part of the structure of nerves. 

 The axis-cylinders, as a continuous formation, pervade all tissues 

 of the body except the horny epidermal tissue, and serve for 

 the transmission of either sensory impressions from the peri- 

 phery to the center, or motor impulses from the center to the 

 periphery. 



Nerve-tissue, as such, is destitute of blood- and lymph- vessels. 



* This chapter will be found more deficient in histological facts than, per- 

 haps, any other of the book. The reason is that I have not as yet given very 

 much time to the study of nerve-tissue, this being the most unsatisfactory and 

 discouraging portion of histology. I prefer, therefore, to be incomplete in 

 this matter until I am able to make positive assertions, based on personal 

 observation, instead of relying too much on what others have said. The par- 

 ticulars that I shall give concerning the architecture of the brain I have 

 taken from the ingenious publications of Th. Meynert. 



