SECT. 4] HEAT-PRODUCTION OF THE EMBRYO 



689 



confirmed by Quajat in 1899, who, however, made no measure- 

 ments of the respiratory quotient, and in 1903 Farkas went into the 

 matter again. He used the same technique as that of Bohr & Hassel- 

 balch on the chick, and his experiments did not begin until about a 

 fortnight before hatching, at which time the sudden rise in the 

 respiration occurs. Farkas' figures were in good agreement with 

 those of Luciani & Piutti; thus in his experiments i kilo of eggs 

 just before hatching evolved 8-7 gm. of carbon dioxide per day, 



Days 

 Leptinotarsa decemlineata 



Days 



Anasa Irisiis 



Fig. 137. {The upper solid line in each figure represents the 0^ intake, the lower solid line the CO^ 

 output, and the dotted line the R.(l-) 



while in theirs i kilo of eggs at the same time evolved about lo gm. 

 A curve constructed from his data is given in Fig. 136. Unfor- 

 tunately, he did not make any determinations of the oxygen uptake, 

 so no respiratory quotient was calculated. 



In 1925 Fink made a careful examination of the respiratory ex- 

 change of 10 different kinds of insects, mostly beetles, using the 

 Krogh differential manometer and Jacobs' modification of the Haas 

 colorimetric method for studying carbon dioxide elimination. Figs. 

 137 and 138, taken from Fink's paper, all show the curves obtained 

 for carbon dioxide output during the embryonic development of 

 beetles. In each case there is what Fink calls a preHminary "forma- 

 tive period", followed by a continuous rise in respiration (grams of 



