1815.] Discovery of the Uses of the Cefehellim. 421 



In the 2Sth number, Mr. Alexander Walker comes forward, 

 strikes Dr. Leach otF the field by giving a flat denial to his most 

 unfounded assertion, and thrusts in a claim for himself to tlie dis- 

 covery. Mr. Walker, in quoting from my letter, begins at the 

 middle of a sentence, and thus makes me appear to deduce a con- 

 clusion from most insufficient data. JNIoreover, he merely quotes 

 my first conjectures on the subject without giving the smallest hint 

 of the decisive expeiiments to which they led. Genuine philosophy 

 ought to expand the breast with candour. 



1 never before saw Mr. Walker's speculations on the nervous 

 system, or knew that they existed. Had I seen the third volume of 

 the Archives before I wrote to you, I would not certainly have 

 claimed the discovery of the quadripartition of the spinal marrow. 

 This discovery, although quite original on my part, belongs, from 

 priority of publication, to Mr. Wal!;cr. Mr. Walker, liowever, 

 has not a\iticij)ated me witii respect to the sacral termination of the 

 spinal marrow. I am the first, so far as my reading has gone, to 

 lift off the caudu equina, and show the marrow terminating at the 

 sacrum in a sharp point like the quill of a porcupine. This disco- 

 very rather militates against the old doctrine that the spinal marrow 

 is just a bundle of nerves proceeding to and from the brain, which 

 doctrine JNIr. Walker has adopted. '' The spinal marrow," he 

 asserts, " serves no other purpose than a nerve would have done la 

 the same situation, alihough from its being protected by the canal 

 of the vertebriE, and the productions of the cerebral membranes, it 

 requires not the strong and more close investments which the nerves 

 possess in order to protect them in their passage among moving 

 organs." (Archives, vol. iii. p. 142.) I, on the contrary, viewr 

 the cerebrum, cerebellum, and spinal marrow, down to the very 

 point of this porcupine extremity, as one continuous organ, which 

 may be styled the animal brain, while the cauda equina, and all the 

 other animal nerves, are merely derivative. 



1 do not know what Mr. Walker means by quoting from the 

 Archives about the cerebellum. His hypothesis regarding the cere- 

 bellum is, that it is the organ of volition ; and he arrived at this 

 $ame hypothesis by the following logical ratiocination. Because the 

 situation of the cerebellum is opj)Osite to the situation of the face, 

 therefore the function of the cerebellum must be opposite to the 

 function of the face ; and it beijrg an understood maxim in physio- 

 logy that se/na/ivn is jiisl diredhj op/josi/c to volition, and as sensa- 

 tion rebides in the face, so volition muM reside in the cerebellum. 

 This doctrine Ls^aid to be corroborated by this sapient consideration, 

 *' that as the grgans of tense and the cerebellum are ihc first and 

 the last portion^, of the nervous .system, .so sensation and volition are 

 the first and the last of its functions." Alihough here the onus 

 probandi lies with Mr. Walker, yet, to put this nbsurd and ground- 

 Jess hy|x>the»is at rest, I may mention that volition rauLs among the 

 faculticb of mind, whose organ is the cerebrum ; and that, ailections 

 »i ike ccrebiuin, while the ccrebcUuui reinaius sound, produce 



