THE NERVOUS SYSTEM. 



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The brain placed upon its base. The knife has passed through the middle of 

 the great commissure or corpus callosum, 1,1, 1, 1, as far as the mfundibulum 

 2, situated below the anterior commissure 3, and as far as the corpora quadri- 

 gemina 4, 4, 4, 4. The two hemispheres are separated and unfolded. The 

 posterior and superior parts of the nervous mass of the spine and brain are seen. 

 The grooves 5, 5, are continuous with the lateral grooves 6, 6. 7. The central 

 fissure. 8, 8. The space before the fundamental part or processus vermiformis 

 of the cerebellum open ; viz. the fourth ventrical : it is in connection, by means 

 of a canal situated below the mass of communication called the valve of Vieus- 

 sens 9, 9, and below 10, with the third ventricle or space, 11, 11, in the midst of 

 the great inferior cerebral ganglion or thalamus opticus 12. The'septum lucidum 

 or common mass of communication and fornix are cut at 1 3, on each side, and 

 entirely removed, in order to expose the great cerebral ganglion 12, 12, and 

 14, 14, 14, 14. On the side A, all the inner surface of the cerebellum is seen cut 

 vertically through the centre. On the side B, the cerebellum has been removed 

 by a horizontal cut from within outwards, and from before backwards, on a level 

 with the white fibres 15, situated in the fourth cavity or ventricle, the fundamental 

 part or vermiform process, and what is seen of the anterior surface of the side A. 

 By a vertical cut in the direction from 13 to 16 (side A), the anterior and inner 

 part of the hemisphere B has been removed, to show the diverging direction of 

 the nervous band above the great inferior ganglion or thalamus opticus, the very 

 fine fibres of grey substance, the great bands 17 in the middle, the direction of 

 this mass of grey substance in the internal part 1 8 and in the external 1 9, and 

 the proportional size of each of these divisions. 20, 20. Commencement of the 

 pyramidal bundle of the cerebrum. 21. Corpus restiforme or original band 

 of the cerebellum. 22. Fourth ventricle or the space before the fundamental 

 part of the cerebellum. 23. Entrance of the pyramids below the pons or 

 great original band of the cerebrum beneath the commissure of the cere- 



