CORRELATIVES OF WATER CONTENT 237 



information is available. Such would be rates of blood flow, of 

 pulmonary ventilation, of muscle shortening, of swallowing. As 

 each physiological function is measured, increasing numbers of 

 correlations become possible, for all that have gone before fit with 

 the new data. 



At present it is inferred that both positive and negative water 

 loads are distributed beyond the blood ; the whole body thus shares 

 in the water. The plasma increases its load by a fraction greater 

 than the remainder of the body does. But I see no evidence that 

 any one ' ' compartment ' ' regularly maintains its volume or concen- 

 tration while others are sacrificed. No tissues store outstanding 

 proportions of water. From data on volumes and concentrations 

 of tissues it is inferred that electrolytes mostly stay where they are, 

 while water added to or subtracted from the body ultimately dis- 

 tributes itself so that vapor tensions are everywhere nearly equal. 

 If solutes are by manipulation added or subtracted with water, 

 other situations result. 



Among the many variables of the organism that are correlated 

 with water load, it seems arbitrary to emphahize any one correla- 

 tive as constituting either a signal or a director of processes con- 

 cerned in recovery, though some are of such a nature that they 

 could serve in that capacity, such as increments of plasma dilution 

 and of plasma volume. Modifications in metabolisms, behaviors, 

 and compositions, whether regarded as unavoidable coincidences 

 or as advantageous adjustments, are at the same time character- 

 istics by which diverse degrees and types of water load may be 

 differentiated and classified. 



