LECTURE XIII.
APRIL 8, 1858.
SPINAL CORD AND BRAIN.
The spinal cord — White and grey matter — Central canal — Groups of ganglioi ►cefli — White columns and commissures. The medulla oblongata and the brain — Its granular and bacillar layer. The spinal cord of the petromyzon and its non-medullated fibres. The intermediate substance (interstitial tissue) — Ependyma ventriculorum — JNeuroglia — Corpora amylacea.
The last time, gentlemen, I laid before you the results of the most recent observations concerning the nature and distribution of the ganglion-cells in the great nervous centres; allow me now to dwell a moment upon that organ which serves as a type in the development of the vertebratse, and is at the same time the one whose structure we can best take in at one view, namely, the spinal cord.
The spinal cord presents, as is well known, and can with ease be seen by the naked eye in any transverse section, in different parts of its course, a different amount of white matter, though nearly everywhere the white matter predominates over the grey. This appears in transverse sections in the form of the well-known horns, which are distinctly marked off from the pure white of the rest of the mass by their sometimes pale grey, some-
