342 



ANATOMY OF THE CENTRAL NEEVOUS SYSTEM. 



The white matter, surrounding the gray, consists principally of longi- 

 tudinally directed fibers, together with the oblique, ascending fibers of the 

 nerve-roots and certain other fibers, which pass out at more or less of a right 

 angle from the gray matter to the white columns. The nerve-fibers have 

 an axis-cylinder and a medullary sheath. The thickness of this sheath varies 

 greatly. They do not possess a sheath of Schwann. 



The axis-cylinder presents a fibrillated appearance, wherever examined. 

 Probably it is made up of numerous fibrils. Recent investigations have 

 shown that the axis-cylinders of the nerve-fibers in the spinal cord, at their 

 extremities, do not end as a whole, but by a kind of splitting. "With all 

 the long nerve-fibers in the white matter and also in the gray matter, one 



ffiitierhorn 



ZeUend Su6st Aotamlo 



Ma/ytnale JI -/wrTizeilen. 



Cenirale //. ■^r/tzeUet'^ 



MasaleM-^iornzeilei 



'::ilal. hint Ori^/Je. 



'-■ MeiJu/itiSru/'pe' — 

 Mediai'e ^ord. dri^/^e/ — ■ 



l^order/tortty 



Fig. 210. — (After Waldeyer, slightly modified 



Sections through 

 Inferior portion of cervical enlargement. 



The divisions are made according to the structures brought out by stain- 

 ing an adult cord with carmine. Other methods show that, at least in the 

 fetal cord, in certain regions there are a great many more individual cells 

 than are here represented. Hhitcrhorn, Posterior horn. Zillni d. Sub. Bol., 

 Cells of the subst. Rolando. Maryinale B.-hormiIle)i, Marginal cells of post, 

 horn. Gcntralc H.-hornzcJIcn, Central cells of post. horn. Bamle H.-hornzeUen, 

 Basal cells of post. horn. Stilling-Glarke Zell., Stilling-Clarke's cells. Mittel- 

 zelleii, Middle cells. Lat. hint, (h'li'ppe, Lateral posterior group. Laterale vord. 

 Gr., Lateral anterior group. Mediale hint. Gruppv, Median posterior group. 

 ilcdiale vord. Griippe, Median anterior group. Torderhorn, Anterior horn. 



Lumbar enlargement. 



finds at certain points that a delicate fibril separates off at right angles to 

 the axis, passes toward the gray matter, and there, as has been observed, it 



