Page:Proceedings of the Royal Society of London Vol 6.djvu/19



LIEUT.-COLONEL SABINE, R.A., V.P. & Treas. in the Chair. A paper was read, entitled "Researches into the Structure of the Spinal Cord." By Jacob Lockhart Clarke, Esq. Communicated by Samuel Solly, Esq., F.R.S. Received October 15, 1850.

The author having undertaken a series of observations with the view of determining, if possible, the relations which appear to subsist between the spinal nerves and the respiratory nervous centres, was led into a more extended inquiry than he at first contemplated, the results of which are communicated in this paper. After stating that the observations were made, by means of a microscope of the best construction, upon many thousand preparations of the spinal cord of Man, of the Calf, Sheep, Pig, Dog, Cat, Rabbit, Guinea-pig and Frog, he describes the methods adopted in making these preparations. The following are the results of his observations.

At the lower extremity of the spinal cord, the posterior gray substance consists of a single mass, formed by the coalescence of the two posterior horns, and consequently the gelatinous substance extends across the middle line. The anterior gray substance, however, is divided by the anterior columns into two distinct horns, which curve inwards and taper to a rounded point. The spinal canal is large and nearer the anterior surface of the cord.

The nerve-vesicles are scattered irregularly through the gray substance.

The fibres of the gray substance are of the tubular kind, and of small average diameter. There are two classes with regard to direction, transverse and longitudinal. Of the transverse, there are two orders, the antero-posterior and latero-transverse.

The antero-posterior are continuous with the posterior roots of the

. 77.