

////: < I:\TH.\I. 



r '/'///: \i-:i;rous SYSTI:V. 



tin rjKJiulymis, eonneetivo tissue, nerve tubes, ncrvo colls, and vessels enter 

 into tlic structure of the medulla. 



The connective tissue of the spinal cord is very delicate, rich in nuclei. :ind 

 belongs to the variety that histologists have named '' reticular " or " adenoid." 



It appears to arise from the pia mater, and forms lamella) that jx -in Irate 

 the nerve-sukstanco to meet and anastomose with each other, and finally 

 become confounded with the epondymis around the central canal. This 

 tissue, which is also named ncuroylia, has been compared to a spon i 

 whose spaces are deposited the other elements of the cord. Thin neurogliu 

 exists in the white and grey substances, but is more abundant in tin- superior 

 than in the inferior grey cornua. It surrounds the upper extremity of the 

 former in becoming softer and more transparent, and is here designated the 

 (jtldtinom substance of Rolando (substantia (jelatinosa). It constitutes, in 

 great part, the grey commissure, and can be deeply stained by the carminato 

 of ammonia. 



TRANSVERSE SECTION OF SPINAL CORD OF MAN THROniH Till; .MIM'I.i; or Till; 



i.i MI:AK KEiiiox, SIIOWINU ON Tin; JMHIIT sim: THE cori:si; m mi; M.I;\I;- 

 I:IM>IS, AND ox Tin; IJ;I-T Tin; i'usrri(t.N OF Tin; rm.NciPAi, II:A< i.> <>i \ rsici I.AI: 

 MATTES. 



A, A, Anterior or inferior columns; r, r, Posterior or superior columns ; L, i., I ,it i.J 

 columns. a, Anterior or inferior median fissure; ;, 1'nslcrinr or superior median 

 fissure; 6, ft, ft, ft, Anterior or inferior roots of spinal nerves; c, c, Posterior or 

 superior roots ; d, d, Tracts of vesicular matter in anterior column ; e, Tracts of 

 vesicular matter in posterior column ; /, Central canal ; </, Substantia gi-latiimsa. 



The tubes and cells form, with the neuroglia, the whole of the grey 

 substance. The cells have at least five prolongations, and the tubes are 

 reduced either to the axis-cylinder (curia-fibre), or to this and a very thin 

 layer of medullary substance. 



The cells are not uniformly distributed in the grey substance, but ore 

 arranged in small masses that constitute three longitudinal columns : 



