NERVE-TRUNKS. 



73- 



the action of osmic acid or special hematoxylin staining (Weigert), the med- 

 ullary substance then exhibiting a dark color and appearing as a deeply 

 tinted ring which surrounds the axis-cylinder. The neurilemma-nuclei are 

 occasionally seen as deeply stained crescentic figures that partly encircle the 



Perineurium 



Epineurium 



Nerve-fibre 



Epineurium 



Blood-vessel 



FIG. 98. Transverse section of funiculus composed of nerve-fibres held together by endoneurium and 

 surrounded by perineurium. X 175- 



nerve-fibres, lying beneath the neurilemma. Viewed in cross-sections, the non- 

 medullated fibres appear as small irregularly round fields arranged in groups 

 that correspond to bundles. When numerous, the latter are aggregated into- 

 secondary bundles between which 

 extend delicate septa of connective 

 tissue, continuous with the gen- 

 eral envelope of the nerve-trunk. 

 The fibres being nonmedullated, 

 their diameter is very small, some- 

 times less than i //. 



The Ganglia. The cell- 

 bodies of the neurones constituting 

 the sensory or afferent paths within 

 the peripheral nerves, as well 

 as .those within the sympathetic 

 (visceral) nerves, are collected into 

 aggregations known as ganglia. 

 Familiar examples of the latter are 

 the spinal ganglia on the dorsal 

 roots of the spinal nerves, certain 

 cranial ganglia (as the semilunar 

 [Gasserian] connected with the fifth nerve, the acoustic with the eighth, and 

 those on the trunks of the seventh, ninth, and tenth cranial nerves), and the 

 sympathetic ganglia along the gangliated cords and within the plexuses of the 

 sympathetic. 



FIG. 09. Transverse section of small splenic nerve con- 

 sisting chiefly of nonmedullated fibres. X 180. 



