INTERRELATIONS AMONG COMPONENTS 415 



siderable modification appears only in increments of y itself. The 

 relation between load and corrective exchange is therefore unique 

 and specific ; the very component that is present in unusual amounts 

 is the one whose exchanges are most modified. The existence of 

 that specificity was guessed in the first place; now that it rests 

 explicitly upon a considerable array of facts, its non-random char- 

 acter is more evident. 



(3) Having found that certain features become easy to grasp in 

 diagrams of interrelations (load of one component plotted against 

 load of another component), how can I formulate multiple corre- 

 lations? Or is it necessary to stop with two or three components 

 at a time? One step might be to represent an additional component 

 in a 3-dimensional diagram. 



In another direction it is possible to proceed by combining com- 

 ponents. Wherever two or more components have the same dimen- 

 sions, their combination may be a sum or a mean; the values 

 obtained, however, preserve the definitions given to each of the 

 components included. Where the dimensions differ, restricted 

 progress is possible, (a) The components may be redefined to 

 make them commensurate in terms of control contents of each ; in 

 terms of standard deviations of each; in terms of lethal loads of 

 each ; in terms of selected coefficients of physical or physiological 

 equivalences (§ 134). (b) A combined load may be represented as 

 a multidimensional sum or product, e.g., x gm./kg. plus y cal./kg. 

 plus z atmospheres; or v gm. X cal./kg. X atm. (c) Tables or 

 alignment charts may represent an unlimited number of compo- 

 nents even though each of them be visibly a separable variable. 



In particular, I believe all the changes measured at any moment 

 during one bout of exercise may be counted up so as to represent 

 the total combined state of the organism. Instead of the two com- 

 ponents represented in fig. 185, some 20 or 30 separable components 

 might enter into one quantitative statement of a physiological state 

 at a chosen moment. 



Combined components actually occur in every science. For cer- 

 tain of them names exist. Any solution is such; cardiac output 

 (heart frequency X stroke output) is another. Water plus certain 

 solutes is plasma; plus heat is warm plasma; plus blood cells is 

 whole blood. So ''biological" terms as well as non-biological ones 

 are often known whereby to designate combinations of properties. 

 For numerous other combinations terms will be forthcoming when 



