Manchester Memoirs, Vol. xlii.{\%gZ\ No. \% 31 



In the second place, others lead away to the cortex 

 of the opposite hemisphere, forming part of that great band 

 of fibres, the corpus callosum, which ties together the two 

 halves of the brain. How far the "callosal fibres" are 

 concerned in bringing it about that, while having two 

 brains we have only one mind, or that, in vision in parti- 

 cular, our daily life makes us no sign of the fact that 

 of the fibres coming from the retina half are gathered up 

 into one hemisphere and the other half into the other, is a 

 matter on which I must not dwell here. 



In the third place, others, and those by far the most 

 numerous, lead to other parts of the cortex of the same 

 side. Such axons, known by the not very satisfactory 

 name of "association fibres," link themselves by their ter- 

 minals or collaterals with cells in some part of the cortex 

 other than the occipital, with cells having functions other 

 than those of the occipital cells. Accepting the general 

 principles on which I dwelt so long, we may infer that 

 whatever be the exact nature of the events which take 

 place in such an "association fibre" from the occipital 

 cortex, as the result of other and different events reaching 

 the cell of which it is the axon, those events lead to events 

 again different in the axon of the cell on which that 

 association fibre impinges. I purposely say events in the 

 axon, rather than events in the cell, meaning by cell the cell 

 body; for those association cells are no more terminal 

 cells than are the occipital cells; in the one and in the 

 other the cell body, with its nucleus, and the den- 

 drites are only means for securing the occurrence of 

 events sweeping along the axon. Indeed, within the 

 central nervous system there are no terminal cells, no 

 terminal units at all. As I have now repeatedly said, 

 the whole nervous system is a congeries of chains, some 

 long, some short. In each chain, whether long or short, 

 there is one kind of beginning, a sensory cell, generally a 



