22O 



THE NERVOUS SYSTEM 



nerve fiber. These fibers seldom run an extended course 

 alone, but are bound together in large numbers to make a 

 nerve trunk. This trunk is composed of a number of 

 bundles of fibers, and is surrounded by a connective tissue 

 membrane known as the epineurium; the separate bundles, 

 or funiculi, are surrounded each by a similar membrane 

 called the perineurium; while inside the funiculi, between 



FIG. 64. Transverse section of a nerve. (Median.) 



ep, epineurium; pe, perineurium; ed, endoneurium. (Landois.) 



the primitive fasciculi, is a delicate supporting tissue known 

 as the end on curium, or the sheath of Henle. In connection 

 with this sheath there are nuclei belonging to the connective 

 tissue and to the nerve fibers themselves. The sheath be- 

 gins where the nerve fibers emerge from the white portion 

 of the centers, is interrupted by the ganglia in the course of 

 the fibers, branches as the bundle branches, and is lost before 

 the terminal distribution is reached. It is seldom found sur- 

 rounding single fibers. It is likewise rare for capillaries to 



