332 THE SPINAL CORD, BY J. GERLACH. 



into its interior, as transverse sections show that there are 

 numerous septulse traversing the white substance, and pene- 

 trating to the grey, which frequently intercommunicate with 

 each other. The difference between these septula, which enter 

 the cord on all sides, and the septum posterius, is that the 

 latter runs in a straight direction to the posterior grey com- 

 missure, whilst the former, branching and anastomosing like 

 the midrib of a leaf, follow no determinate course. The 

 connective tissue of the white substance is consequently to be 

 regarded as a plexus of variously sized trabeculse, in the meshes 

 of which the nerve fibres run for the most part in a longitudinal 

 direction. The vessels pursue the same course as the tra- 

 beculse of the connective tissue. The size of these trabeculse 

 may be easily ascertained from transverse sections. The 

 strongest, which proceed directly from the layer of con- 

 nective tissue immediately investing the spinal cord, measure 

 from 0'015 to 0'020 of a millimeter, becoming gradually 

 attenuated by frequent subdivision, till they do not exceed 

 O'OOS of a millimeter. The area of the more or less rhomboidal 

 spaces bounded by these trabeculse amounts in transverse 

 sections to 0*03 0'09 of a square millimeter. 



The layer immediately surrounding the cord, and the trabe- 

 cular plexus proceeding from it, present quite peculiar structural 

 relations, which indeed have given occasion to the establishment 

 of a separate tissue, the so-called nerve cement, or neuroglia. 

 The external thicker portion of the investing layer, as well 

 as the central part of the trabeculse arising from it, still pos- 

 sesses the well-known structure of fibrillar connective tissue, 

 consisting of slightly sinuous fasciculi of the very finest con- 

 nective-tissue fibrillse, running horizontally in relation to the 

 vertical axis of the body. After being treated with alkalies, 

 which cause the fibrillse to disappear, a few fine elastic fibres 

 come into view. In chromic-acid preparations that have been 

 treated with solution of carmine, and especially well after the 

 addition of very dilute acetic acid, cellular elements become 

 visible, with deeply stained nuclei, and more or less numerous 

 and sometimes branched processes that can be relatively easily 

 isolated, which is probably the consequence of the prolonged 

 action of the chromic-acid compounds. 



