24 



CONARIO-HYPOPHrSIAL TRACT. 



" cerebrum " or " cerebral hemispheres " in Vertebrates. It 

 is divided^ as already remarked, from the " suboesophageal 

 ganglions," completing the totahty of the brain in Inverte- 

 brates (fig. 3, 2,, fig. 9, b), by the extension of the gullet and 

 mouth to the aspect of the body which bears relation to, or 

 corresponds with, that of the main centres of the nervous 

 system — such centres answering, as to the parts they supply 

 and, in Articulates (fig. 3, i), in their continuous extent, to 

 the myelon (fig. 3, i) and ep- mesencephalon (fig. 2, 3, 4) in 

 Vertebrates. This homology, however^ Cuvier did not admit ; 

 . and herein he has had the support ofdater anatomists. With 

 respect to the myelon — moelle epiniere " — marked tt in 

 his diagram*, he expressly states that it is peculiar to the 

 type of structure exemplified in his figure A (fig. 1.0) (of the 

 Quadruped) f. But no evidence is adduced against the 

 homology of the elongate moto-sensory tract, or neural axis, 

 in Articulates, and the elongate moto-sensory but seemingly 

 non-ganglionic tract, or neural axis, in Vertebrates, save their 

 diff'erent relative positions in a standing or walking Badger 

 or Beetle. Cuvier assumed, as Gegenbaur and other anato- 

 mists have done, that the surface or aspect of the body in 

 progressive motion determines the homology of such surface, 

 and that the surface nearest to which lies the neural axis in 

 Articulates answers to that which is furthest from such axis 

 in Vertebrates. But there are both Vertebrates and Inver- 

 tebrates in which, during progressive motion, neither the 

 neural nor the hsemal surface is downwards or next the 

 earth. 



The subcesophageal mass or ganglions in Cephalopods send 

 * Tom. ext. pi. xii. 



t " 1 1, la moelle epiniere propre au Mammifere," torn. cit. p. 257 (re- 

 ferring to his subject as a representative of a Yertebrute animal). 



