NORMAL PROCESSES OF ENERGY METABOLISM 641 



the feedings are; two hours or more apart, and if easily assimilable sugars 

 are added to the milk the quotient will he even higher. For example, an 

 infant four months of age was given a dextri maltose formula and the 

 respiration experiments were begun on different days at successively longer 

 intervals from feeding with the following results: 



Time After Feeding Jt Q. 



18 minutes 0.79 



33 " 0.82 



1 hour 30 minutes 1.00 



From this point the quotient usually falls progressively (see page 

 G31). Benedict and Talbot's (a, b) data show many cases like the fol- 

 lowing : 



Schlossmann and Murschauser(d), however, often found quotients as high 

 as 0.84 and 0.85 as much as 18 to 20 hours after last food. No details re- 

 garding the composition of the food taken at the last feeding are given. 



The fact that the respiratory quotient is higher soon after a meal 

 (and progressively falls from a point which may be placed at 1 to 2% 

 hours thereafter depending on the formula) does not denote accelerated heat 

 production, for it will be remembered that carbon dioxid has a lower heat 

 value when the quotient is high than when it is low (see page 567), 



Another reason why an ordinary feeding of milk does not raise the 

 heat production in an infant is the interesting fact first recognized by 

 Rubner that protein retained for growth does not raise the heat produc- 

 tion. In truth one can say that any foodstuff retained for growth does 

 not raise the heat production. It is only when a surplussage of digestive 

 products enter the circulation that oxidation of them is accelerated by 

 adding more fuel to the fire or by stimulating the intracellular processes. 

 In the infant or any other stage of active growth (pregnancy or convales- 

 cence) the materials entering the circulation are retained with greater 

 avidity by the cells and therefore are not exposed to the destructive oxida- 

 tions to the same extent as in the normal adult. Hoobler(&) has made 

 this point as regards protein an object of special study in an infant, with 

 the following results : 



