Blood : a study in general physiology / by Lawrence J. Henderson.

  • Lawrence Joseph Henderson
Date:
1928
Catalogue details

Licence: In copyright

Credit: Blood : a study in general physiology / by Lawrence J. Henderson. Source: Wellcome Collection.

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    grees of oxygenation, with the help of contour line charts. A third aspect is defined by the familiar equation, [h+] , [H2CQ3] [BHC03]’ which is the analytical expression of a similar Cartesian nomogram. The possibility of thus dealing with three variables at a time is nothing but the expression of the fact that, aside from variations in p02 and pC02, the blood is assumed to be subject to no change in composition, although in certain special cases this restriction is unnecessary. The fact that it is possible thus to define the variations of any three variables, independently of the other four, may readily be demonstrated as follows: Choose any three scales, say u, v, and w, on figure 40. Then, if values of any two of the three variables are given, e.g., uXy vx, or u2, w2, or v3, the third is determined. This is true be¬ cause two points determine a straight line and the inter¬ section of this line with the scale of the unknown variable determines the value, wx or v2 or u3, of this variable. Now among 7 variables, taking 3 at a time, there are 35 combinations. Accordingly, the three cases above men¬ tioned are but three among 35 cases necessary for an ex¬ haustive description. Moreover, in each of these 35 cases three variables are involved. Accordingly, it is possible, in each case, to construct three contour line charts, taking in turn u and v, u and w, and v and w as the correlatives of x and y, the Cartesian coordinates. Thus a complete treatment involves the construction of 105 Cartesian con¬ tour line charts. These 105 charts fall into 21 sets of five each. There are, in fact, 21 combinations, taking two at a time, among seven variables. Therefore, there are 21 pairs of Carte¬ sian coordinates. When two of the variables have been chosen as Cartesian coordinates, five remain. Accordingly, they yield five families of contour lines. Evidently the five members of each of these 21 sets of contour line
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