Red blood cells: why or why not?

It is commonly stated that, if hemoglobin were dissolved in the blood plasma rather than enclosed in corpuscles, the viscosity of the blood would be greatly increased. We found that when the corpuscles of dog or goat blood were disrupted with ultrasound, giving a solution with the same hemoglobin concentration, the relative viscosity was drastically reduced. It appears, therefore, that the existence of blood corpuscles does not contribute to a reduced viscosity of blood.