156 



PHYSIOLOGICAL REGULATIONS 



are obtained by difference the supposed total circulating "cells" 

 volumes. Exchanges of "cells" are very much slower than of 

 "plasma." Rates of recovery of volumes are derived from the 

 differences between pairs of successive measurements ; but each of 

 them varies in absence of load by a coefficient of difference of about 

 ±: 3 per cent (table 6), and hence some of the data are statistically 



TABLE 6 



Coefficients of difference (CA) in volumes of distrihution in three species of mammals. 



CA represents 1/^/2 times the root viean square of percentage differences 



between successive tests on 3 to 6 individuals 



Distribuend 



Number of paired tests ... 

 Interval between tests, 



hours 



CA of ' ' plasma ' ' volume, 



% of mean 



CA of "blood" volume, 



% of mean 



Source of data 



Dog 



Vital red 

 4 



0.32 



1.11 



1.77 

 Smith ('20) 



Man 



Vital red 

 5 



170 



3.47 (C.V.) 



Sunderman 

 and Austin 

 ('36) 



Eabbit 



Trypan red 

 12 



0.33 



3.08 



2.84 



Trypan red 

 6 



1.0 



2.91 



5.26 



Takahashi ('3.5a) 



insignificant. Nevertheless all average exchanges of "blood" and 

 of ' ' plasma ' ' are of such a sign that recovery is occurring. Further, 

 reciprocals of increments in concentrations of various other con- 

 stituents whose circulating amounts are assumed to be fixed, such 

 as hemoglobin, solute refractive index, and colloid osmotic pressure 

 (Onozaki, '35; Nagaoka, '36), indicate proportional changes of 

 water content of the same signs. 



The responses to loads are both qualitatively and quantitatively 

 comparable to the net equilibration of water content or body volume 

 in the dog (fig. 16) or other organism as a whole. Net equilibra- 

 tion thus presents a like pattern, regardless of the fact that entirely 

 diverse processes and tissues are concerned in the exchanges of 

 fluid. 



No means has been found of ascertaining what over-all volume 

 is both gained and lost during equilibration, or during turnover. 

 Hence total rates are not recorded, as they are for the whole dog 

 or rabbit, but only net rates of exchange. The rate of turnover 

 might be enormous, for it is believed that plasma in every capillary 

 both gains and losses liquid continuously (Schade, '27). Corre- 

 spondingly the fluctuating variability of ' ' plasma ' ' volume, which 



