12 THIRD REPORT — 1833. 



however, the bony canals were so cautiously divided as to leave 

 their internal membranous investment uninjured, these ab- 

 normal motions were not produced. It is, therefore, in these 

 membranes, or rather in the expansion of the acoustic nerve 

 which overspreads them, that the cause of this phenomenon 

 must reside. No explanation is proposed by Flourens of the 

 control thus exercised by a nerve supposed to minister exclu- 

 sively to the sense of hearing, over actions so entirely opposite 

 in character. It is remarkable that the irregular movements 

 should observe the same direction in their course as the canals, 

 by the section of which they are induced. Thus the direction 

 of the inferior vertical canal is posterior, that of the superior 

 is anterior, corresponding perfectly with the directions of the 

 abnormal motions. 



Medulla Oblongata. — The medulla oblongata, or "bulbe 

 rachidien," is reducible into six columns, or three pairs, viz. 

 two anterior or pyramidal, which partially decussate, two mid- 

 dle or olivary, and two posterior or restiform, which proceed 

 forwards without crossing. It is continuous in structure with the 

 spinal marrow, and enjoys, by virtue of this relation, the same 

 function of propagating motion and sensation. But it is distin- 

 guished from the spinal medulla by special and higher attributes, 

 being endowed with the faculty of originating motions, as well 

 as with that of regulating and conducting them. The medulla 

 oblongata, with the cerebrum and cerebellum, constitute, in short, 

 according to Flourens *, those portions of the nervous system 

 which exercise their functions "spontaneously or primordial- 

 ly," and which originate and preside over the vital actions of 

 the subordinate parts. To this latter order of parts, which re- 

 quire an exciting or regulating influence, belongs the spinal 

 medulla. In the superior class, Flourens seems to assign even 

 a higher place to the medulla oblongata than to the cerebrum 

 or cerebellum. For the cerebrum, he observes, may act without 

 the cerebellum; and this latter organ continues to regulate the 

 motions of the body after removal of the cerebrum. But the 

 functions of neither cerebrum nor cerebellum survive the destruc- 

 tion of the medulla oblongata, which seems to be the common 

 bond and central knot combining all the individual parts of the 

 nervous system into one whole. 



The medulla oblongata was regarded by Legallois as the 

 mainspring or "premier mobile" of the inspiratory movements. 

 He repeated before a Commission of the Institute of France the 

 leading experiments on which his opinion rested f. In a rabbit 



* Memoires de I'Academie des Sciences, torn. ix. p. 478. 

 t CEuvres de Legallois, torn. i. p. 247. 



