“…Though this was originally suggested by Poiseuille (1846), based on his studies of Newtonian fluids in rigid tubes, this relationship has never been investigated directly in humans. Gelin et al (1961), Carey et al (1965, and Gianelli et al (1965) measured the effect of various intravenous infusions on blood flow but did not correlate the changes in blood flow with the changes in viscosity or P.C.V.…”