X1VJ NERVE FIBRES 115 



Non-medullated nerve fibres. 



Non-medullated fibres readily become varicose after death, 

 and when treated with fixing agents. The following method 

 gives good results ; a bundle of the splenic nerve of any animal, 

 or a grey ramus of a rabbit, is taken immediately after the 

 death of the animal, pinned out so that the fibres are straight, 

 fixed with osmic vapour (cp. p. 162) for 2 to 3 hours, placed in 

 Flemming's fluid for 2 to 3 hours or till next day, washed in 

 running water, stained with hsematoxylin (this may be done 

 later, on the slide), imbedded, and transverse sections cut. In 

 such sections the fibres are circular, about 2/x, in diameter, the 

 outei* part (sheath) stained deeper than the core ; nuclei are 

 seen here and there in the core. 



The core of the non-medullated fibres may be stained in 

 the fresh nerve with methylene blue ; the nerve is teased out on 

 a slide and before it becomes dry a drop of '06 p.c. methylene 

 blue in *75 p.c. sodium chloride is added, this is left for 15 to 

 20 minutes, by which time examination with a low power should 

 show fine blue filaments, probably varicose ; a cover-slip is then 

 put on, with or without replacing the methylene blue with salt 

 solution, and examined with a high power. 



Nou-medullated nerves cut off in the body from their nerve 

 cells retain for a long time their ordinary appearance when 

 treated with osmic acid and teased out, they are however 

 smaller owing to the disappearance of the core; the absence 

 of the core may be determined by treating the fresh nerve with 

 methylene blue. 



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