CH. VII.] 



NERVE. 



101 



a number of minute transverse bands in the axis cylinder 

 (Fromann's lines), which is here not closely invested by the 

 medullary sheath. 



The arrangement of the nerve-fibres in a nerve is best seen in 

 a transverse section. 



The nerve is composed of a number of bundles or funiculi of 



Fig. 123. Section across the second thoracic anterior root of the dog, stained with osmic 

 acid. (Gaskell.) 







nerve fibres bound together by connective tissue. The sheath of 

 the whole nerve is called the epineurium ; that of the funiculi 

 the peinneurium ; that which passes between the fibres in a funi- 

 culus, the endoneurium (fig. 122). 



The size of the nerve-fibres varies ; the largest fibres are found in 

 the spinal nerves, where they are 14^4 to 19/1 in diameter.* Others 

 mixed with these measure i '8 to 3 '6/1. These small nerve-fibres are 

 the visceral nerves ; they pass to collections of nerve-cells called 



u ?= micro-millimetre = ^ millimetre. 



