Effects of Chemical Agents on the Nervous System. 27 



Agassiz during his last two Sojourns at Le Hotel des Neuchitelois, upon 

 the Lower Glacier of the Aar, in the years 1841 and 1842 ; by M. E. 

 Desor ; vol. xxxv., p. 166 — continued through several Numbers of this 

 Journal. 10. On the Classification of Fishes ; by Professor Agassiz ; 

 vol. XXX vii., p. 132. 11. On Fossil Fishes ; by Professor Agassiz ; vol. 

 xxxvii., p. 331. 12. Remarks on Professor Pictet's Treatise on Palaeon- 

 tology ; by Professor Agassiz ; vol. xxxix., p. 295. 13. On Fossil Fishes, 

 particularly those of the London Clay ; by Professor Agassiz ; vol. xxxix., 

 p. 321. 14. Remarks on the Observations of M. Durocher, relative to 

 the Erratic Phenomena of Scandinavia ; by Professor Agassiz ; vol. xl., 

 p. 237. 15. On the Ichthyological Fossil Fauna of the Old Red Sand- 

 stone ; vol. xli., p. 17. 



Researches into the Effects of certain Physical and Chemical 

 Agents on the Nervous System. By Marshall Hall, 

 M.D., F.R.S., Foreign Associate of the Royal Academy 

 of Medicine of Paris, &c. (With a Plate.) Communica- 

 ted by the Author. 



(Concluded ft-om vol. xlv., p. 267.) 



Section IT. On the Electrogenic Condition of the Spinal Marrow, 

 and of the Incident Spinal Na^es. 



In the former section of this paper I gave an account of 

 the electrogenic condition of the nervous system, in its sim- 

 plest forms, viz., as induced in the muscular nerves ; and I 

 detailed the influence of moisture, which is analogous, I be- 

 lieve, to its simultaneous discharge ; of dryness, which is 

 equivalent to its interrupted discharge, together with its own 

 peculiar effect ; of restricted or extended points of Voltaic 

 contact, and of various modes of connection of the wire pro- 

 ceeding from the voltaic apparatus, or of the nervous and 

 muscular structures together, and with each other. 



That paper may be regarded as strictly preliminary to the 

 present one, in which I propose to treat of the electrogenic 

 state in the spinal marrow and in incident nerves, and, more 

 at length, of the collateral experiments to which I have al- 

 luded in the concluding part of the preceding paragraph. 



I have hitherto avoided all speculations on the nature of 

 the various phenomena or conditions induced. I would still 

 carefully distinguish between any such speculations which 

 the present paper may contain, and the phenomena or facts 



