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 deriyed from ganglio-genetic cells forming the roof of the 
vesicle, 
g. 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 arc reflex and automatic, 
or, to use the language of Meinert, fori distinct projection 
systems. 
to. That these isa distinct analogy between the Vertebrate 
and Arthy Lean, as Gaskell and others have suggested, 
but that ou. kuowiledge of the Arthropod brain is far too incom- 
plete to avc.y of any exact comparison of the parts of the brain 
in these t,o great divisions of the anima! kingdom. 
33 
