CORRELATIVES OF WATER CONTENT 



219 



be inferred that water loads do not merely dilute the solids of 

 plasma in a lump, the increment of refractive index per unit of dry 

 weight differing slightly for various solutes. Rather, diverse con- 

 stituents are diluted unequally, as is to be expected from the fact 

 that their volumes of distribution are not all alike. 



Again, at diverse + AW, blood chloride dilutions (fig. 124) and 

 serum electrical conductivities (1/ECs, fig. 125) are measured, and 

 their relationships are ascertained graphically or by equation; 

 usually AE = cAW. Such relationships are often termed ' ' empiri- 



"0 .064 .070 .076 .082 .088 



Plasma Concentration = Dry Weight /Wet Weiqbi 



Fig. 123. Eefractive index of plasma (RI) in relation to fraction of solids in 

 plasma (D/F). Heparinized plasma of dog. Two individuals (C, open points; G', 

 solid points) in 21 tests; given water by stomach, or deprived of water with constant 

 diet, or neither. The ordinates on the outer RI scale, readings for plasma of the dipping 

 refractometer at 17.5° C. minus the similar reading for distilled water. The correlation 

 coefficient is + 0.963 ; the least-squares regression line shown does not pass exactly through 

 the origin. Data of Adolph and Kingsley. 



cal"; they are just as valid as "physico-chemical" ones, the chief 

 differences being that they are more difficult to predict, are worked 

 out in vivo instead of in vitro, and sometimes have larger devi- 

 ations. 



This, however, is the sort of correlation that exists among all 

 the quantities that are each separately related to the body water 

 content. Under the specified conditions, variables AM, AN, AP, and 



