THE SPINAL CORD. 



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Steucture. — Independently of the epithelium mentioned when describing 

 the ependymis, neuroglia, nerve-fibres, nerve-cells, and vessels enter into the 

 structure of the spinal cord. 



The neuroglia has been compared to a kind of sponge (the so-called spongy 

 matter), in the spaces of which are the other elements of the cord. It exists in 

 the white and the grey matters, but it is more abundant in the superior grey 

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

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

 gelatinom substance of Rolando (substantia gelatinoso Rolandi). It constitutes, 



TRANSVERSE SECTION OF SPINAL CORD THROUGH THE MIDDLE OF THE I,UMBAR REGION, SHOWING 

 ON THE RIGHT SIDE THE COURSE OF THE NERVE-ROOTS, AND ON THE LEFT THE POSITION OF 

 THE PRINCIPAL TRACTS OF VESICULAR MATTER. 



A, A, Inferior columns ; p, p, superior columns ; L, L, lateral columns ; a, inferior median fissure ; 

 p, superior median fissure; 6, 6, 6, h, inferior roots of spinal nerves; c, c, superior roots; 

 d, d, tracts of vesicular matter in superior column ; e, tracts of vesicular matter in inferior column 

 /, central canal ; g, substantia gelatinosa. 



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

 of ammonia. 



The neuroglia is associated with a small quantity of connective tissue, which 

 enters the cord along with the vessels. It is formed of a mass of cells, the mem- 



regions either a depression on the surface of the cord, or on its substance a fasciculus of 

 connective tissue, or a vessel larger than in other points. 



The systematic lesions of the cord not having yet been observed in the domestic animals, it 

 cannot be stated at what point the distinctions established in the human spinal cord are justified, 

 so far as that of the Horse is concerned. In some sections of the cord of that animal, it would 

 appear that the fasciculus of Tiirck is distinct from the other parts of the anterior column ; 

 but in a great number the separation is extremely vague. The columns of Goll alone are very 

 distinct in the superior portion of the cervical region. They are especially visible in the Dog. 



In fact, at the present time the topography of the human spinal cord cannot be without 

 uncertainty when applied to that of animals ; but the efforts of pathologists and anatomists 

 should be directed to dissipating this uncertainty. 



