Answering my own question: in vivo, tissue sizes (weights) increase
pretty much proportionately with body weight, but the total perfusion
rate of each tissue increases approximately as surface area, or body
weight raised to the 2/3 power. So perfusion per unit volume or unit
mass of tissue is generally higher in smaller critters, in keeping
with metabolic rates.
I talked with a pathologist, and looked at some numbers on the amount
of blood volume in the vasculature of each tissue, and these seem to
be about constant.
-Paul Schlosser
