SPINAL CORD 



233 



than in the white portion ; and arteries of considerable size may 

 frequently be found.) (h) Peri-vascular lymphatics. (Find an 

 artery in transverse section, and observe the clear space around it, 

 which may be mistaken for the result of contraction of the tissue 

 in hardening. Careful study will reveal minute branches of cells, 

 passing between the adventitia of the blood-vessel and the wall of 

 the lymph -space.) 



The course of the axis-cylinders in the cord, and their relations 

 with the ganglion-cells of the gray matter, are extremely intricate. 

 The Gelgi method, in the hands of Ramon y Cajal and others, 

 has been the means of clearing up many of the obscure parts of 

 this subject. The limits of the present work will only permit of 



FIG. 151. 



LARGE GANGLION-CELLS OF THE ANTERIOR HORN OF THE SPINAL CORD. 

 Low POWER. PHOTOMICROGRAPH. 



allusion to a few of the most important facts. In this connection, 

 it is well to recall the description and diagram of a neurone (page 

 222). The central nervous system is supposed to consist of many 

 neurones. According to this theory, several neurones may operate 

 together, one superimposed on another. It is to be remembered 

 that the processes of ganglion -cells probably do not anastomose 

 with those of other ganglion -cells. 



The large ganglion-cells of the anterior horns of gray matter 

 give off axis -cylinder processes to the anterior motor nerve-roots. 

 Some ganglion -cells (column cells) have axis -cylinder processes 

 which run vertically in the white matter of the anterior and lateral 



