fi9 

 fibre extanls eatirely to the limitaas exterrin, thnt it benra 

 no branches, th'it its course is frre frooi sharp tur-is, airJ that 

 its diameter is variei by nodes ani thickenin>5S of various 

 shapes ani sizes, Groups of these fibres forn radiating bands 

 through the fornaatio reticularis, and their evident purpose is 

 to provide stays for the vast number of longitudinal and arcu- 

 ate nerve-fibres .vhich characterize this part of the oblongata. 



The epenlyma attains its highest differentiation in the 

 lobus vagi; see Pig. IT. The fibres do not reach the surface, 

 and they give origin to a most complicatei series of branches 

 at the level occupied by the neurones of the lobus. The prox- 

 imal part of the fibre is quite stout and some.vhat irregular 

 in its course. The distal part becomes dissolve! in branches, 

 the terminal t^igs of which are minute. The interlacing branch- 

 es forn a support for the neurones anl nerve-fibres proper to 

 this region. 



b. Xeur-ogUa. — The neuroglia of the oblongata is, like 

 the epenlyma, present, in great diversity of form, but the va- 

 rious elements are referable to two general classes. One, the 

 well-known astrocyte, is distribatei in every part of the ob- 

 longata where thare are ner/e-fibres in numbers — in the roots 

 of nerves, in special tracts, in centres where many fibres have 

 their teruination, and in the formatio reticularis. The special 

 form of the astrocyte depenis, to some extent at least, upon 

 the densit/ with which the nerve-fibres are arrangel. At points 



