1 18 MEMOIR OF MAGENDIE. 



What the Italian did not see or saw but incompletely, and M. Magendie has 

 placed beyond dovibt, is : 1st, that this liquid exists in all ages : 2dly, in the 

 normal as well as disordered state; 3dly, that it is deposited not in tlae cavity 

 of the arachnoid, but below that membrane, around the encephalon and the me- 

 dulla; 4thly, that the pia mater is its secreting organ; 5thly, that there is a 

 particular point, called by M. Magendie the entrance of the ventricles, by which 

 tlie liquid penetrates from the exterior of the brain into the cavities, into the 

 VI -iiricles, the conduits of that organ. 



" Is it not remarkable," he says on this occasion, " that the parts of the brain 

 named by the ancient anatomists valvula, aquce-ductus, fons, have precisely the 

 use which their name indicates % The valvida of Viensses, or the great valve 

 of the brain, fulfils, beyond doubt, the functions of a valve, since it resists the 

 egress of the liquid which traverses or which fills the fourth ventricle. No part 

 could better merit its name than the aqueduct of Sylvius, since, according to the 

 experiments which I have reported, this canal conveys sometimes the water of 

 the ventricles towards the spine, and* sometimes from the spine towards the head. 

 Lastly, what is called the pons is, in effect, a great medullary arcade, inverted 

 and placed below the current of the liquid which traverses the aqueduct." — 

 {Journal de Physiologie, t. vii, p. 29.) 



A great anatomist of recent times, Soemmering, even places the scat of the 

 soul in the liquid of the ventricles of the brain: "If it be permitted us to assign 

 a peculiar organ to the common sensorium, or if there be a proper seat for the 

 common sensorium in the brain, it is not without some show of reason to be 

 sought for in this liquid."* 



APPENDIX II. 



ANALYSIS OF THE EESEAECHES OF SIE CHARLES BELL ON THE NER- 

 VOUS SYSTEM, t 



In order to convey a clear idea of the merits of M. Bell, and the particular 

 character of his new views on the nervous system, it is necessary to say a word 

 respecting the doctrines which prevailed, previous to his time, on that important 

 subject. 



"If we pass in review," says M. Bell himself,. " the opinions respecting the "^ 

 brain and nerves which have been held at different times, we find one theory 

 which had been maintained from the Greek authors down to the age of Willis, 

 and which has been transmitted, with few changes, to modern authors." Now, 

 this theory which had passed from the Greeks to Willis, and from Willis to 



ital foramen, encloses the spinal marrow, like a sheath, to the termination of the os sacrum. 

 Yet this tnbe of the dura mater is not so wide as to reach everywhere the circuit of the cavity 

 of the spine, nor so narrow as to embrace closely the included medulla; but is somewhat 

 distant from the cavity of the spine, chiefly behind and at the place of the apophysis, and is 

 at the same time separated by a considerable space from the periphery of the medulla which 

 it encloses. Now, this space between the vagina furnished by the dura mater and the mar- 

 row, is always full, not with medullary matter, nor, as some learned men in so obscure a 

 subject have conjectured, with a vaporous exhalation, but with water, similar to that which 

 the pericardium confines around the heart, which fills the hollow spaces of the ventricles of 

 the brain, the labyrinth of the ear, and, in short, all the cavities of the body from which the 

 free air is to be excluded, &c. (Dominici Cotunni : De Ischiade Nervosa Co7nmentarius, Vi- 

 enna, 1770.) 



* Peculiare organum sensorii communis siponere fas est, vel si propria sedes sensorio com- 

 muni incerebro est, haud sine veri quadam specie hoc in humore quteri debet. — (De Corporis 

 Humani Fabrica, vol. iv, p. 69, 1798.) 



t In this analysis of the researches of Bell there will doubtless be some repetition of what 

 has been said in the Memoir or Notes, but it is not the less needed in order to present the 

 complete filiation of ideas. 



