76 



NERVE 



[CH. VII. 



not closely invested by the medullary sheath (fig. 93). Macallum 

 has shown that this appearance of transverse striping is an artifact 



Fio. 93. Several fibres of a bundle of medullated nerve-fibres acted upon by silver nitrate to show 

 behaviour of nodes of Ranvier, M, towards this reagent. The silver has penetrated at the nodes, 

 and has stained the axis-cylinder, M, for a short distance. S, the white substance. (Klein and 

 Noble Smith.) 



and can be obtained in any exposed portion of an axis cylinder, that 

 is, wherever the silver nitrate can penetrate to it. 



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

 transverse section. 



FIG. 94. Transverse section of the sciatic nerve of a cat about x 100. It consists of bundles 

 (funiculi) of nerve-fibres ensheathed in a fibrous sheath, epineurium, A ; each bundle has a special 

 sheath (not sufficiently marked out from the epineurium in the figure) or perineurium B ; the 

 nerve-fibres N / are separated from one another by endoneurium ; L, lymph spaces ; Ar, artery ; 

 V, vein ; F, fat. Somewhat diagrammatic. (V. D. Harris.) 



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

 fibres bound together by connective tissue. The sheath of the whole 



