972 ENERGETICS AND ENERGY-SOURCES [pt. m 



as measured by Bohr & Hasselbalch in each period of 24 hours is 

 compared with the heat production calculated from the oxygen 

 consumption (Col. 9, Table 124), it will be seen that the agreement is 

 fair, though the experimental is always rather lower than the calcu- 

 lated value. The fact that the calculated value assumes fat only to be 

 burnt would not entirely account for this. Returning to Table 123, 

 however, it can at once be seen that the basal metabolism invariably 

 exceeds the total amount of heat evolved. Thus there is not enough 

 heat eliminated to account for the quantity that ought to be produced 

 in maintenance energy alone. The basal metabolism as here calculated 

 must be far too high, for if all the increments are added up the result 

 is 61,000 calories, or about four times as much as the total energy 

 known to be lost by combustion. We must therefore suppose either 

 that the surface formula does not hold in embryonic life or that the 

 high temperature (37°) in which development proceeds leads to a 

 lower basal metabolism than would be expected. Lusk says that the 

 minimum requirement for energy is seen to be present when the 

 fasting organism is surrounded by an atmosphere having a tempera- 

 ture of 30 to 35°. Most important of all, however, is the probability 

 that Rubner's constant for the chick does not hold for the embryonic 

 chick. It is quiescent, its muscles have no tonus or very little, its 

 respiratory muscles are inactive, and its heart alone is constantly re- 

 quiring a supply of energy. Since the metabolism is proportional to 

 the superficial area of the animal, it may well be asked what is 

 happening in an embryo at the minute stage when its percentage 

 growth-rate is 1400 (Schmalhausen). 



7-5. Apparent Energetic Efficiency 



Evidently it is not possible to calculate the "rendement ener- 

 getique reel" (R.E.E.) for the chick. But Terroine & Wurmser 

 pointed out that some of the discrepancy existing between Tangl 

 and Rubner might be removed if it were known. For the growing 

 cow the R.E.E. was calculated by Kellner & Kohler, and for the 

 growing pig by Fingerling, Kohler & Reinhardt. They estimated 

 the magnitudes of [a) the energy stored in the organism following 

 the addition to a fundamental ration of a given foodstuff in 

 known quantity, calculated on the basis of carbon and nitrogen 

 balance and formation of tissue; (b) the total energy catabolised 

 measured by indirect calorimetry, and {c) the "energie d'entretien" 



