||"The authors [Strumia and Phillips 1963 PMID 13993198] concluded that the relative viscosity of whole blood depends upon the relative volume of the red cell mass, regardless of the size and number of the individual red cells constituting the mass. However, Gregersen et al. (primary source) found an influence of erythrocyte size on blood viscosity at low shear rates. They used bloods with the following mean corpuscular volumes: goat, 18.2: dog, 66.0: man, 91.6: and elephant, 119.7 µm^3. At a shear rate of 0.05 sec^-1, the viscosity at all hematocrits increased in the order: goat, dog, man, elephant, but at 0.5 sec^-1 the differences were not as apparent. In contrast, the differences were insignificant when the cells were suspended in Ringer solution."