702 THE RESPIRATION AND [pt. iii 



include data for abnormal oxygen concentrations, cannot help us 

 here, and Hasselbalch's observations on nitrogen excretion still remain 

 mysterious. 



The observations of Bohr & Hasselbalch on the heat production 

 of the hen's egg were published in 1903. They knew the amount of 

 oxygen used and carbon dioxide excreted, and the amount of fat 



Table 82. Respiratory quotients of Chick. 



21 o-68o — — • — — 



burned. They rightly regarded it as very important to know whether 

 the energy of the fatty acids could all be accounted for as heat put 

 out during development, and, if not, what proportion of it could be. 

 With this aim in view they constructed a differential calorimeter in 

 which they were able to incubate single eggs and examine the heat 

 production of them at the same time as their gaseous exchange. The 

 figures they obtained were very numerous. Attention may first be 

 directed to the respiratory quotients, which are collected together 

 in Table 82 and in Fig. 144. Five series are available, those of Bohr 



) 



