UNIFORMITIES AND COMPARISONS AMONG COMPONENTS 393 



to the organism (table 41), the order being nearly the same in two 

 mammalian species. Among anatomically more diverse species it 

 is probable that somewhat greater physiological differences also 

 will appear. 



When the compensatory equilibrations in an organ and in a 

 whole individual are compared, it will probably be found that the 

 latter has (l) adjustments to more components, and (2) greater 

 independence of adjustments among the several components. Ade- 

 quately to test (l) is difficult within a human lifetime. Statement 

 (2) has not been rigorously tested. If the man receives water with 

 any known combination or quantity of solutes, contents of water 

 and solute are eventually restored. But no one organ in situ is 

 known to recover fully without the whole body recovering. And 

 no isolated organ so recovers, to present knowledge. Here are 

 outlined two of the many quantitative methods of comparing 

 regulations in the organism and in its parts. 



It is a temptation to suppose that the compensations of the whole 

 body are prerequisite to the recoveries of each compartment in it. 

 For instance, the maintenance of body B might enable maintenance 

 of ''extracellular" volume V, it in turn enables maintenance of 

 cell L, and it in turn enables maintenance within it of Golgi body N. 

 The dog regulates heat content in B, but such regulation is un- 

 known for any V or L of the dog's body. On the other hand, the 

 properties by which N, L, or V exchange water with their sur- 

 roundings may be just as prerequisite to B's water maintenance 

 as the reverse. All the units are coordinate, so far as I perceive, 

 each of them regulating its components in its own sphere and 

 fashion; there is no tenable distinction between prerequisites and 

 postrequisites. 



Comparative physiology evaluates the differences among spe- 

 cies, and the same data that manifested the uniformities serve also 

 to indicate the contrasts among living units. Quantitative differ- 

 ences need not depend on anatomical or chemical differentiations, 

 and may be finer distinctions than they. Whereas biochemical 

 tables list the compositions, potentials, and catalysts of several 

 species, physiological tables comprise their rates of change in 

 selected states. Comparisons have in the past usually been limited 

 to those between two species and in respect to one component in 

 one load. Evidently any scheme that coordinates the information 

 of numerically diverse loads, and is capable of serving for all spe- 



