p. L. BLACKSHEAR AND R. J. FORSTROM 
527 
[■ I I I I I I I I — I 1 — I 1 1 1 L-J 
Figure 4. — Photomicrographs of erythrocytes from 
nine animal species at the same magnification (10 fi 
scale at bottom). Edge view of mammalian RBC 
is that for rouleaux in autologous plasma except 
goat RBC, for which rouleaux were formed in 2% 
Dextran (M. W. ~ 10°) solution. In non-mammalian 
RBC, nuclei are visible in both views, (from ref. 1). 
shear dependence parameter is defined as the 
difference in viscosities at a high (5.2 sec^^) 
and a low (0.52 sec~^) shear rate divided by 
the viscosity at the high shear rate. The rela- 
tionship between shear dependence and tend- 
ency to aggregate is shown in Figure 7 versus 
fibrinogen level. 
Recall from Figure 2 that the two factors 
which determine the shear dependence of viscos- 
ity are cell deformability and tendency to ag- 
gregate. But from the above we see in mam- 
malian RBC the tendency to aggregate is also 
a function of cell deformability. Finally recall 
that deformability is related to sphericity index 
which in turn appears to be a monotonic func- 
tion of cell volume. Thus the rheological be- 
havior of the blood of an experimental mammal 
should be predictable by a knowledge of plasma 
viscosity, hematocrit and cell volume. 
COMPARATIVE STRENGTH OF MAMMALIAN 
RED BLOOD CELLS 
In this section we will attempt to show that 
the membrane stress at which hemolysis occurs 
T i \ 1 r 
2 4 6 8 10 1 
FILTER PORE DIAMETER (m) 
Figure 5. — Relation between normal RBC transmission 
through polycarbonate sieves and sieve mean pore 
diameter (from Ref. 1). 
Table I. — Dimensions of Erythrocytes (from Shu Chien, et al.) 
Diam. X Diam. X Thickness Surface area Volume Sphericity Index Nucleus MCHC 
(tiXuXli) (H^) (fi') (4.84V=/VA) (nXn) . (g%) 
Mammals 
Goat 3.0-4.5 X 1.6 42 18 0.80 — 35.6 
Sheep 4.8 X 4.8 X 1.7 60 37 0.78 — 35.2 
Dog _ 7.5 X 7.5 X 1.6 126 74 0.65 — 34.8 
Man 8.4 X 8.4 X 1.6 152 90 0.64 — 33.5 
Elephant 9.2 X 9.2 X 1.7 181 112 0.62 — 36.2 
Non-mammals 
Turkey _. 13.9 X 8.0 X 2.5 249 136 0.51 6.0 X 3.0 33.6 
Turtle... 19.7 X 12.7 X 3.5 513 394 0.51 6.6 X 4.3 33.5 
Frog- 28.0 X 15.6 X 6.0 1102 823 0.38 10 X 6.7 28.5 
Amphiuma 65.0 X 30.0 X 13.5 6605 10,800 0.36 24 X 15 26.2 
