Royal Society. 243 



to diyness and calcined ; but it was found, contraiy to the state- 

 ment of Berzelius, that the whok-. of the sulphuric acid coidd not 

 be expelled by heat ; it was therefore separated by nitrate of 

 baryta, and the excess of baiyta removed by a httle ^mmonia 

 and carbonate of ammonia ; the iiltered liquid, evaporated and 

 strongly calcined, left piu'e vanadic acid, which was weighed as 

 such, the author finding the method of determining its weight 

 from that of the hydi'ated oxide far less accui'ate. 



XXXIV. Proceedings of Learned Societies. 



ROYAL SOCIETY. 



[Continued from p. 169.] 

 December 5, 1850.— Lieut.-Col. Sabine, V.P. & Treas., in the Chair. 



A PAPER was read, entitled " Researches into the Structure of 

 the Spinal Cord." By Jacob Lockhart Clarke, Esq. Commu- 

 nicated by Samuel Solly, Esq., F.R.S. Received October 15. 



The author having undertaken a series of observations with the 

 view of determining, if possible, the relations which appear to sub- 

 sist 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 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 bj' 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 are 

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



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

 nerves, and probably with the anterior roots. The latero-transverse 

 stretch between the opposite sides of the gray substance, forming its 

 transverse commissure. 



Longitudinal Fibres. — Those of the gelatinous substance, have the 

 characters of minute tubular fibr(!s, presenting dark outlines and 

 frequent varicosities. Their average diameter is the i2;iirith of an 

 inch. They have no nuclei as generally stated, and have no resem- 



112 



