Note 75 — Chapter I

It is possible that an active expansion of the bloodvessels does not take place, but only a contraction. It has been lately denied that there are any nerves of vascular dilatation (inter alia by Dr. Morat, La Semaine médicale, 1892, p. 112). But the effect may be the same in both cases. For through the contraction of the vessels in a single brain-circuit, the dislodged blood would be driven to other portions of the brain, and these would experience a greater access of blood, just as if their vessels were actively dilated.