ON CEREBRO-SPINAL LYMPH 71 



contiguity, and with the different parts of the body, 

 through axonal fibres (Fig. 4) and interpolated ganglia 

 and ganglionic cells, the entire parts being divisible into 

 the systemic and connected sympathetic areas these two 

 areas being intimately related by histological continuity, 

 although to a great extent independent of each other in 

 their respective functional roles. The two systems, 

 however, constitute a united congeries of structures of 

 unbroken histological continuity, or intimate contiguity, 



FIG. 5. SECTION OF THE SPINAL CORD WITHIN ITS MEMBRANES (UPPER 

 DORSAL REGION. (Key and Retzius.) Magnified. 



a, dura mater ; b, arachnoid ; c, septum posticum ; d, e,f, subarachnoid trabeculae, 

 those at/]/", supporting bundles of a posterior nerve-root ; g, ligamentum denti- 

 culatum ; h, sections of bundles of an anterior nerve-root ; k, /, subarachnoid 

 space. 



arranged within a definite series of protective and 

 insulating media, known according to the various parts 

 of the nervous system involved, as the meninges of the 

 brain and cord, and the neurilemmar coverings of the 

 nerve trunks and fibres, separated by a series of inter- 

 spaces, continuous and conterminous with them, which 

 are in turn filled by a fluid, commonly described as the 

 cerebro-spinal (Fig. 5). 



This fluid, the cerebro-spinal, has hitherto been mainly 

 regarded as confined to the inter-meningeal spaces of the 

 brain and cord and the intra-cerebro-spinal spaces (the 

 ventricles and central canal), and has had a very limited 



