PROCEEDINGS 



OF 



THE ROYAL SOCIETY. 



December 5, 1850. 

 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 sub- 

 sist l>etvveen 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 prepara- 

 tions. The following are the results of his observations. 



At the lower extremity of the spinal cord, the posterior gray sub- 

 stance consists of a single mass, formed by the coalescence of the 

 two posterior horns, and consequently the gelatinous substance ex- 

 tends 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 sub- 

 stance. 



The fibres of the gray substance are of the tubular kind, and of 

 small average diameter. There are two classes with regard to di- 

 rection, transverse and longitudinal. Of the transverse, there ar?. 

 two orders, the antero-posterior and latero-transverse. 



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



Proceedings of the Royal Society. Vol. VI. No. 77. 1 



