398 PHYSIOLOGICAL EEGULATIONS 



Volume, V, any volume in U measured by a specified procedure. 

 Usually a volume of distribution (Vd) of a distribuend added to or 

 subtracted from U. 



Dilution, E, reciprocal of concentration of some substance or 

 physical colligative found in some part of U that was analyzed. 



It may be piously hoped that few inferences will be drawn from 

 the terms used in this nomenclature, that would add to the mean- 

 ings conferred by the methods of measurement as actually used. 

 In so far as each term is an abstraction, it is only so by virtue of the 

 fact that similar measurements were employed for similar data. 

 If these actual methods be kept in view, it may be more difficult 

 than otherwise to wander far into metaphysics from the phenomena 

 and relations so described. 



<^ 144. General summary 



All the quantitative correlations in this investigation fall into a 

 very few types. Each type includes those correlatives having cer- 

 tain dimensions ; hence to summarize them it is only necessary to 

 refer to the nine classes of variables (§ 101). Taken two at a time 

 the correlations would fall into 36 types. In actuality those utilized 

 were more limited than this; in nearly every case either time or 

 load was one correlative ; hence, at most, 15 types prevailed. A few 

 of these correlations were common enough to merit special names ; 

 these were : 



Load vs. time, the tolerance diagram. ACoct. Ex- 

 amples, figures 180 (A), 1. 



Rate of exchange vs. time, the exchange diagram. 

 Rcxt. Examples, figures 180 (B), 2. 



Rate of exchange vs. load, the equilibration diagram. 

 R oc AC. Examples, figures 110, 13. 



Particular portions of tolerance curves, or curves for particular 

 components, are currently designated by special names. Thus, 

 there are insulin sensitivity curves, contraction curves, elimina- 

 tion curves, accumulation curves, and penetration curves. Simi- 

 larly, particular kinds of exchange curves are diuresis curves, 

 excretion curves, and age curves. 



It seems to me that by the classification of those and other vari- 

 ables, and of those and other correlations, into a few types, a huge 

 mass of data assumes manageable proportions. Instead of a be- 



