XVII.] 



NERVE-FIBRES. 



209 



(/>.) (H) Select a bundle. Observe the perineurium, made up 

 of several concentric lamellae with nuclei between them. The cut 

 ends of the fibres varying 

 in diameter. 



(r.) Xote in each fibre 

 the section of the stained 

 axis-cylinder. Surround- 

 ing this a clear trans- 

 parent ring, indicating 

 the position of the myelin. 

 which has been dissolved 

 out in the process of pre- 

 paration. 



(d.) Outside this a thin 

 circle the primitive 

 alieath. Between the 

 nerve-fibres a small 

 quantity of connective 

 tissue or endonemium. 



Non-Medullated Nerve- 

 Fibres. 





FIG. 190. T.S. of Several Funiculi of the Median 

 Nerve, p. Perineurium ; ep. Epineurium ; ed. En- 

 doneurium. 



7. Non-Medullated or 

 Sympathetic Nerve - 



Fibres. (i.) These are readily found in the large splenic nerve of 

 the ox, or in a portion of the sympathetic nerve of the thoracic or 

 abdominal chain. The nerve has a pretty thick sheath. Cut this 

 open, and cut off a small piece. Tease it in 

 normal saline. The process of teasing is 

 greatly facilitated by placing the nerve for 

 twenty-four hours in dilute acetic acid (5 drops 

 in 100 cc. water). 



(H) Observe that there are very few medul- 

 lated fibres, the great majority being non- 

 medullatod (iig. 192). Their outlines are not 

 very distinct ; they arc faintly striated longi- 

 tudinally, and have oval nuclei at intervals. 

 They may be stained with picro-carmine. 



(ii.) Place the cervical sympathetic nerve of 

 a rabbit in .25 per cent, osmic acid for 



twenty-four hours. Wash it in water, and stain it for several 

 hours in picro-carmine. Tease a fragment in glycerine. 



(iii.) Or tease the vagus of a rabbit upon a dry slide, taking care 

 that the nerve does not become dry. Cover it for 5-10 minutes 



O 



FIG. 191. Non-Medullater 

 Nerve - Fibres, Sympa- 

 thetic Nerve of Rabbit, 

 x 200. 



