ON THE NEUROGLIA 293 



protoplasmic products, of the cell, and nucleus, respec- 

 tively, it would be hazardous to guess, nevertheless, we 

 think there is evidence to demonstrate that it is not 

 alike, as is to be seen in a well-known illustration at 

 page 310 of Quain's Anatomy (tenth edition), where the 

 axis cylinder has projected its substance, to a considerable 

 distance beyond its surrounding, and accompanying, tubule 

 of white, or medullary, substance. This may, of course, 

 be due to the different, or variant, action, of the reagents 

 employed, on the differing structures of the medullary 

 and axis cylinder protoplasms, respectively, but it, at 

 any rate, proves, that these two substances, can move at 

 different, and independent rates, under the influence of like 

 stimuli, or reagents. The sequence of the material 

 changes occurring in the neuro-metabolic digestive proce- 

 dure thus described, represents a process of developmental 

 ascent from the elementary, or non-organised, to the 

 organised, or complex, and is attributable to the operation 



FIG. 120. VIEW OF THE CEREBKO-SPINAL AXIS. (After Bourgery.) 1. 



The right half of the cranium and trunk of the body has been removed by a vertical 

 section ; the membranes of the right side of the brain and spinal cord have been 

 cleared away, and the roots and first part of the fifth and ninth cranial nerves, and 

 of all the spinal nerves of the right side, have been dissected out and laid sepa- 

 rately on the wall of the skull and on the several vertebrae opposite to the place 

 of their natural exit from the cranio-spinal cavity. 



F, T, O, cerebrum ; C, cerebellum ; P, pons Varolii ; mo, medulla oblongata ; 

 ms, >n s, point to the upper and lower extremities of the spinal marrow; c e, on 

 the last lumbar vertebral spine, marks the cauda equina ; v, the three principal 

 branches of the nervus trigeminus ; C I, the sub-occipital or first cervical nerve : 

 Cvni, the eighth or lowe?.t cervical nerve; D I, the first dorsal nerve; D xn, 

 the last dorsal ; L i, the first lumbar nerve ; L v, the last lumbar ; S I, the first 

 sacral nerve ; S v, the fifth ; Co I, the coccygeal nerve ; s, the left sacral plexus. 1 



1 The relation between the bodies and spines of the vertebrae and the places of 

 attachment of the nerve-roots to the cord is also illustrated by this figure. For 

 more detailed information on this point the reader may consult Cowers, The 

 Diagnosis of Diseases of the Spinal Cord, 1880. 



FIG. i2i. ANTERIOR AND POSTERIOR VIEWS OF THE MEDULLA OBLON- 

 GATA AND SPINAL CORD WITH SECTIONS. (Allen Thomson. ) \. 



The cord has been divested of its membranes and of the roots of the nerves. A is an 

 anterior, B a posterior view. In these figures the filiform prolongation, repre- 

 sented separately in B', has been removed ; C shows a transverse section through 

 the middle of the medulla oblongata; D, a section through the middle of the 

 cervical enlargement of the cord ; E, through the upper dorsal region ; F, through 

 the lower ; G, through the middle of the lumbar enlargement ; and H, near the 

 lower end of the conus medullaris. 



i to 6 refer to parts of the medulla oblongata ; the remaining numbers to parts 

 of the spinal cord. 



i, pyramids ; i', their decussation ; 2, olivary bodies ; 3, lateral columns ; 4, 

 posterior surface of the medulla oblongata ; 4', calamus scriptorius ; 5, funiculus 

 gracilis ; 6, posterior lateral columns passing to the side ; 7, 7, anterior median 

 fissure of the spinal cord ; 8, 8, antero-lateral impression corresponding to the 

 attachments of the anterior nerve roots ; 9, 9, posterior median fissure ; 10, 10, 

 postero-lateral groove; x, tapering extremity of the cord; X, X , in B', filum 

 terminale. 



