DIVERSE COMPOlSrENTS 



327 



measurements of food intakes after prolonged food excesses, nor 

 precise information upon the tolerated loads attained by overfeed- 

 ing. Altogether, however, the form of the equilibration diagram is 

 the same for total substance (fig. 158) as it is for water. 



At zero load, turnover rates of total substance show small vari- 

 ability. Illustrative data are for the rat, in which species the 

 amount of food consumed varies in daily periods only 10 per cent of 

 the mean. It is sometimes said that food intake is habitual, and 

 this expresses in one phrase the fact that many undefined factors 

 are present in maintenance of every species, and recognizes a gov- 



6 h 



X 



4 - 



(2 



o 2 



O 



o 



a: 



-20 



-10 +10 



Load of Total Substance 



Fig. 158. Initial rate of exchange of total substance (% of Bo in first 1.0 hour) 

 in relation to imposed load of total substance (body weight) (% of Bo). Rats were 

 deprived of food and water for 0, 1, 2, or 4 days, or given excess of food and some 

 water on one day; then were allowed to recover. Most of the exchange is water. At 

 the dash line, exchange during the hour would equal load. New data. 



ernor-like action in all of them. The epithet habitual does not 

 recognize the actual fact that a rat is not fooled into continuance 

 of eating when food has already been introduced by stomach or 

 peritoneum. 



It is well known that in deficits approximate balances of intake 

 and of output may be struck that are much smaller than turnover 

 at zero load. Such rates may be visualized in figure 153. But it 

 may not be assumed that load is stationary if a rate of intake is 

 artificially adjusted to equal an expected rate of output. For in 

 that state, rate of output may reach some other lower value. 

 Rather, the situation in both deficits and excesses is delineated (for 



