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PHYSIOLOGY FOR BEGINNERS 



of a peculiar substance of a fatty nature, and is called the 

 medullary sheath or medulla. Covering this is the outer 

 sheath, a thin and delicate membrane, called the neuri- 

 lemma. The axis cylinder in the centre of each fibre is a 

 continuous strand, which generally extends all the way from 



FIG. 80. To illustrate the structure of n^-i-ve fibres. 



A. Nerve fibre examined fresh. /;, node. 



13. Nerve fibre with neuraxis shaded, and medulla represented by dark lines. H.C, 

 nucleus ; /, granular cell substance near the nucleus. 



C. More highly magnified. i, medulla ;,, node. 



D. Nerve treated with reagents to show the neuraxis, ti..r, surrounded by medulla, tit. 



E. Nerve treated with reagents to show n.c, nucleus with fine line over it represent- 

 ing the neurilemma, and outside this fine coiiiu c live tissue c ; .<', nucleus 

 lying in the fine connective tissue. 



I 1 ". Nerve fibre deprived of its neurilemma showing medulla broken up into fr.igim-iiK, 

 w, surrounding the neuraxis n..r. 



the central nervous system to the ending of the nerve fibre 

 in the muscle, or skin, or sense organ, as the case may 



