348 



PHYSIOLOGICAL EEGULATIONS 



about the rate of lactate turnover, only net rates of exchange having 

 been ascertained. Lactate thus represents the many substances 

 that enter metabolism, undergo disposal, and are suitable for the 

 study of temporal relations in equilibration of content. 



M 



+ 02 +0.4 +0.6 +0.8 



ean Lac+icAcid Load~qmyi.cf blood 



Fig. 174. Eate of lactate disposal in relation to lactate load. Man. Disposal is 

 measured by disappearance from the blood during the first 0.5 hour of recovery. Tri- 

 angles; one individual studied by Margaria et al. ('33). Evidence is adduced for the 

 belief that 1 gm. lactic acid/liter of blood equals 0.9 gm. or 10 millimols lactic acidAg- 

 of Bo. Square, mean of the tests with injected lactate by Dietrich and Zeyen ('32) 

 shown in figure 173. The line of ordinates is drawn at zero lactate in blood. 



§ 123. Summary 



A great number of bodily components may be studied in a man- 

 ner similar to those that have been exhibited. The number is by 

 no means limited to chemical constituents, as is thoroughly shown 

 by the study of heat. Some of the same data as are used for heat 

 could be used to illustrate the equilibration of the component body 

 temperature as such. Portions of the data for total substance are 

 available as equivalents of total potential energy content and its 

 various fractions. Other data not mentioned may contribute to the 

 study of body weight or surface, total concentration, specific grav- 

 ity, osmotic pressure, electrical capacity, electrical charge, and 

 many other measurable quantities. That the components named 

 all have physical and chemical terms, merely expresses the fact 

 that properties of living units depend upon non-biological instru- 

 ments for their measurement. 



Sometimes the content of the component in the body, or its in- 



