Merely because something has gone wrong in some blood-vessel or nerve-fibre, all my strength and intelligence seem to fail me.
The same might happen in the case of a bone, of a cartilage, or of a nerve-fibre.
Here it is evident that there can be no rods and cones, their place being wholly occupied by strands of nerve-fibre.
So, in the brain, every sensation is the ring of a cerebral particle, the effect of a momentary impulse sent along a nerve-fibre.
In a usual way, a given class of nerve-fibre is only stimulated by one kind of stimulus.
