476 PHYSIOLOGICAL REGULATIONS 



In general, two or three variables and their mutual relations 

 can be comprehended at one time. Any two or three of the quanti- 

 ties mentioned above : components, exchanges, time, paths, species, 

 parts, tissues, metabolisms, or velocity quotients, or any other vari- 

 able that anyone selects, may be the features about which an ac- 

 count is built. The number of such accounts is only limited by the 

 minuteness of subdivision made in defining each variable, a minute- 

 ness that is often an asset. 



The number of "dependent" variables, and the number of 

 ''degrees of freedom," in an organism can probably never be con- 

 sidered finite. Even if someone were able to demonstrate that all 

 had been found, it would still be possible to redefine some, and 

 subdivide others. 



Since all these studies were touched upon in the course of the 

 investigation as carried out, their multiplicity dispels any notion 

 that the methods used are peculiar to the specific system of vari- 

 ables dealt with, or to the search for regulations. The interrela- 

 tions to be ascertained appear to be limited only by human capaci- 

 ties to compute them and comprehend them. There probably are 

 not many short-cuts to understanding the organism. 



§ 178. Contributions made 



What particular aspects of regulations were emphasized, and 

 what uniformities have been ascertained by inductions from the 

 quantitative data presented above ? 



(1) The relations of a bodily component were compared in 

 diverse species of animals, particularly with reference to its con- 

 tent, exchanges, time factors, and changes of coincident physiologi- 

 cal properties. 



(2) Variabilities of content indicated both the usual limits of 

 content, and the intensities of processes that opposed variations 

 of it. 



(3) Displacements and disturbances of content beyond the 

 usual, made possible the study of rates of recovery, the kinetics of 

 physiological adjustments. Increments of content were usually 

 exponential with time. 



(4) Correlations of rates of exchanges with contents of the 

 same component (equilibration diagrams) portrayed the parts 

 played by gains and by losses in the regain of usual states in the 

 organism. 



