Fig. 4. Instantaneous hematocrit measured in an unanesthetized trout before, during (4.1 min period between broken vertical lines) and following hemorrhage of 35% of estimated blood volume. There is a rapid fall in hematocrit concomitant with hemorrhage and a slow decline thereafter. The slow phase can be described by a mono-exponential decay (solid line) and extrapolated back to the onset of hemorrhage in order to determine the contribution of both rapid and slow processes to the observed hematocrit. In this example, hematocrit is predicted to change from 32 to 25.6 during the fast phase and from 25.6 to 16 during the slow phase, the latter with a half-time of 22 min.