THE VARIATIONS DURING LIFE 



TABLE XIX. 



10? 



Bohr and Hasselbalch [1900] have studied the carbon dioxide pro- 

 duction of the embryo of the common fowl. Later Hasselbalch [1900] 

 determined also the oxygen absorption, and finally Bohr and Hasselbalch 

 [1903] measured the heat production together with the total respiratory 

 exchange. The special merit of these investigations lies in the care- 

 ful determinations of the weight of the embryo at all stages. Table XX 

 and fig. 31 show the CO 2 production and the corresponding weight 



for each stage. 



TABLE XX. 



In series a eggs from different hens belonging to the same race were incubated. In 

 series b eggs from the same hen were used throughout. The determinations of CO 2 pro- 

 duction were made on one single egg. 



1 During the first days CO 2 is given off from the shell. 



2 The figures for the fourth and eighteenth day have been obtained by interpolation. 



