966 ENERGETICS AND ENERGY-SOURCES [pt. iii 



adopt, the more the O.E, will be. It has often been maintained, 

 e.g. by Johansson, that animals have no expenses of this kind to meet, 

 on the ground that, when Meyerhof caused erythrocytes to cytolyse 

 inside a calorimeter, he observed no increased heat production, yet 

 the same worker's results on sea-urchin's eggs could be adduced on 

 the contrary side (and see also p. 985). In any case, the complex pro- 

 cesses of cytolysis would have to be eliminated in some way if a serious 

 attempt was being made to assess the O.E. directly. The conclusion 

 to which we come, then, is that one calorie of energy contained in 

 yolk and white can ttransform itself into one calorie of energy con- 

 tained in feathers, muscles, blood and brain, without any loss of energy 

 except that necessitated by the living cells in their quality of living 

 cells, i.e. more or less inefficient machines. But apart from this 

 necessary expenditure of energy, apart from the universal income 

 tax extorted from all living cells by virtue of their constitution, the 

 transformations of the egg seem to go on without appreciable cost, 

 and the organisation of the animal appears from nowhere, strangely 

 devoid of physico-chemical antecedents. Such a conclusion is intel- 

 lectually unsatisfactory, and in the future attempts will certainly be 

 made to demonstrate the existence of a definite O.E. and to measure 

 its magnitude^. 



It is necessary at this point to consider again the theoretical 

 work of Rubner on the energy relations in embryonic life. His 

 experiments on the storage of food-material in early post-natal life 

 led him, as we have seen, to the conclusion that the formation of 

 I kilo of mammahan tissue required 4808 Cal. (i.e. total absorption, 

 combustion plus storage), and that in pre-natal life it required about 

 4000 cal. (2500 for combustion and 1500 for storage). It is evident 

 that the efficiency here is very low, but attention may for the time 

 being be concentrated on the absolute magnitude of the combustion 

 quota. Tangl noticed that Rubner's "law of intra-uterine develop- 

 mental energy" seemed different from what his own results on the eggs 

 of the lower animals would have led him to expect. Thus to build i kilo 

 of silkworm during its embryonic life 



Calories 



t/ (Rubner) or Ea. (Tangl) 875 



W (Rubner) or specific energy-content 1352 



2227 



^ There may also conceivably be a quota of energy used in establishing the O.E.; this 

 quota will form part of the Ea. 



