XXII. Further researches on the grey substance of the spinal cord

Abstract

Since the appearance of my second series of investigations on the structure of the Spinal Cord, certain modifications in the method I employ have enabled me to carry my inquiries to a still greater extent, and in many respects beyond the limits of what was actually known on this important subject. By this modified method the elementary nerve-tissues undergo less alteration from their natural state; for the most minute nerve-cells and their processes, as well as the finest fibres, are permanently preserved, and display a sharpness of outline unattainable by any other mode of preparation employed at the present day; while sections the one-twelfth of an inch in thickness may be rendered perfectly transparent. Many of the older anatomists, from Bartholinus downwards, had observed that the grey substance of the spinal cord is softer, more delicate and more vascular than the surrounding white columns; but Rolando was the first to point out a diversity in its structure. He observed, chiefly in quadrupeds, that on each side the posterior third of the grey crescent consists of a peculiar cineritious substance, which presents a different aspect from that which forms its two anterior thirds: it is different in colour, darker, and less red. Rolando, however, assigned too large a space to this "new substance,” which does not comprise so much as the posterior third of the grey crescent, but forms only a comparatively narrow and curved lamina or band around the extremity of each cornu, and, when viewed in a thin section by transmitted light, is found to be actually much paler and more transparent than the rest of the grey crescent. That this lamina is the part indicated by Rolando appears evident on examining his plates.