THE DEVELOPMENT OF THE NERVOUS SYSTEM. 495 



7. That the central ganglia and crura are developed in con- 

 tinuity with the ventral chain of ganglia. 



8. That the small cells of the whole cortex of the cerebron 

 are derived from ganglio-genetic cells forming the roof of the 

 vesicle. 



9. That the large cells which surround the white matter in 

 the newly-hatched larva are similar to those from which the 

 post-oral centres are developed, and that they are probably 

 some of them converted into ganglion cells, whilst others are 

 concerned in the development of the central stroma ; and that 

 the nerve-cells so developed are possibly more intimately con- 

 nected with the central ganglia, and are concerned in other 

 functions than those of conscious sensation. In other words, 

 it appears to me that the parts derived from the roof of the 

 vesicle are concerned in consciousness and volition, whilst those 

 derived from the primitive ganglia are reflex and automatic, 

 or, to use the language of Meinert, form distinct projection 

 systems. 



10. That there is a distinct analogy between the Vertebrate 

 and Arthropod brain, as Gaskell and others have suggested, 

 but that our knowledge of the Arthropod brain is far too incom- 

 plete to allow of any exact comparison of the parts of the brain 

 in these two great divisions of the animal kingdom. 



33 



