154 



PHYSIOLOGICAL REGULATIONS 



accompanying "plasma" volumes (fig. 95) are the same volumes of 

 distribution of trypan red, injected anew at each measurement. 

 Transfusion of citrated rabbit blood suddenly enhances both vol- 

 umes ; hemorrhage suddenly diminishes them. Thereafter, changes 

 are most rapid immediately following the experimental procedure ; 

 indeed comparisons of the volumes actually injected or withdrawn 

 with the loads measured by the trypan red procedure, show that the 

 fastest adjustments of ''plasma" volume occur in the minute dur- 



Hours 



Fig. 94. Course of volume load (% of Vo) during recoveries from the transfusion 

 of citrated rabbit blood (open circles) and from hemorrhage (solid circles). Eabbit, 

 mean body weight 2000 gm., 5 to 8 individuals and tests. The volumes concerned are the 

 volumes of distribution of trypan red (given by vein) divided by the hematocrit ratios. 

 The enveloping broken lines indicate standard deviations ; these are 2 to 3 times the stand- 

 ard errors. Data of Takahashi ('35a, '35b). 



ing which the transfusion, and especially the hemorrhage, is ad- 

 ministered. "Plasma" fully recovers its initial volume within 0.5 

 or 1.0 hour, while whole "blood" does not. 



During an arbitrary interval of time between the first and sec- 

 ond measurements of trypan red volume, the rates at which each 

 volume changes are compared (fig. 96). Following an excess of 

 volume produced by transfusion, the "blood" volume decreases; 

 following a deficit of volume produced by bleeding, it increases. 

 From the total "blood" volumes and the total "plasma" volumes, 



