OF THK CEREBRO-SP1NAL SYSTEM, 7| 



also all other sensations acquire distinctness and durability; the spinal cord combines 

 the muscular, contractions so as to produce motion in the joints ; and the cerebellum 

 regulates these movements, and unites them so as to constitute the actions of standing- 

 and locomotion : such are the discoveries of M. Flourens*." 



III. jQf the distinct Functions of the anterior and posterior Columns of the Spinal Mar- 

 row. It is certain that the spinal marrow sends oft' nerves engaged in the performance 

 of two distinct functions, viz. that of feeling- and that of motion. From what part 

 we are led to ask of this organ, do the nerves allotted to each of these functions pro- 

 ceed ? It is well known that the spinal marrow is formed of two substances a white 

 substance, which is exterior, and a gray substance, occupying the interior of the cord, 

 The continuity of the fibres composing the roots of the spinal nerves with the latter, 

 as established by Keuifel and Ollivier, naturally leads us to suppose that it is particu- 

 larly concerned in the production of these functions. It may be also observed, that 



* Experiments, similar to those of M. Flourens were instituted, in 1805, by profes- 

 sor Rolando, of Turin, from which he deduced inferences in some respects the same 

 as those at which M. Flourens has arrived. The experiments of the latter physiologist 

 were, however, more varied, were, apparently, more carefully performed, and there- 

 fore were more conclusive, than those of his predecessor. They were repeated, more- 

 over, before a commission of the institute of France, composed of some of the most 

 eminent of that body, who approved of the conclusions which are given above. The 

 following are the inferences which M. Flourens considers that his experiments justify. 



1. " No movement proceeds immediately from the will. The will is the exciting and 

 determining cause of certain movements ; but it is never the efficient or effective cause 

 of any. 



2. " It has been shown that the immediate cause of muscular contraction, particu- 

 larly resides in the spinal marrow and nerves, and that the regulating cause of these 

 contractions is placed in the cerebellum. 



3. " There are, therefore, three phenomena essentially distinct in a movement pro- 

 ceeding from volition : 1, the volition of movement, a volition which seems to reside in 

 the cerebral hemispheres : 2, the appropriate regulation of the different muscular con- 

 tractions productive of motion, which reside in the cerebellum : and 3, the excitation 

 of these contractions, which has its efficient seat in the spinal marrow and its nerves. 



4. "As these three phenomena, essentially distinct, reside in three organs also dis- 

 tinct, the possibility of abolishing any one of them, and leaving the others uninjured, 

 seems apparent ; thus the will may be destroyed, and the regulation of contraction it- 

 self will remain : or both volition and the regulating cause of contraction may be 

 abolished, and contraction will alone be produced, &c. 



5. " There exists, therefore, in the nervous system, (cerebro-spinal system,) three 

 properties essentially different : one, the exciter of motion ; the other the regulator / 

 and the third, the -wilier and perceiver. 



6. "The spinal marrow, the medulla oblongata, the tubercula quadrigemina, alone 

 possess the property of directly exciting muscular contraction ; the cerebral lobes and 

 cerebellum do not possess it. 



7. " There are two ways of destroying vision without g'oing beyond the cerebral 

 mass : one by the removal of the tubercula quadrigemina producing loss of the sense 

 of sight, the other, by the removal of the cerebral lobes, causing the loss of the sen- 

 sation of sight. 



8. " There is, therefore, in the cerebral mass, distinct organs for the senses, for.the 

 sensations -, for the movements. 



9. *' Not only all the sensations, all the perceptions, all the volitions, all the intellec- 

 tual and sensitive faculties reside exclusively in the cerebral lobes, but all these facul- 

 ties occupy jointly the same seat in these organs ; for if one of them disappear, all 

 disappear ; and if one return, all return. The power of feeling, willing, and per- 

 ceiving constitute therefore but one faculty, residing but in one organ. 



10. " The cerebral lobes, the cerebellum, the tubercula quadrigemina, may lose a 

 considerable, bat limited, portion of their substance, without losing the exercise of 

 their functions ; and they may re-acquire them after being totally deprived of them. 



11. " The spinal marrow and the medulla oblongata, are the only parts which directly 

 affect the same side of the body, with that in which they are themselves aifected. 

 The tubercula quadrigemina, the cerebral lobes, and the cerebellum alone produce 

 their effects upon the opposite side to that in which they are influenced ; the former 

 act in a direct course, the latter in a cross direction." 



