658 THE RESPIRATION AND [pt. iii 



much attention should be paid to the exact shape of the curve, 

 but only to its general form. It is very interesting that the heat- 

 production rate should be for the first 3 hours after fertilisation 

 a constant. This does not agree with the results of the other two 

 workers, who found that the rate of heat-production rose during 

 early development more or less parallel with the respiratory rate. 

 The rate of heat-production of the unfertilised Arbacia e^g, according 

 to Rogers & Cole, is o-o8 gm. cal. per hour, and during the 2-cell 

 stage 0-52 gm. cal. per hour, figures which are distinctly higher than 

 those found by Shearer and by Meyerhof. 



It is evident, however, that the percentage increase is just the same. 

 Rogers & Cole drew no conclusions from these facts, but there is some 

 likelihood that their figures are more accurate than those of the earlier 

 workers, for, where slight losses of heat are the most probable cause 

 of error, we ought perhaps to accept the highest figures as the best 

 ones. It was obviously worth while to calculate calorific quotients 

 for Arbacia again on the basis of the highest figures for heat-production, 

 and this I did in 1927. Unfortunately Rogers & Cole never made 

 any estimations of oxygen consumption on their eggs, and, although 

 Loeb & Wasteneys stated in 19 10 that they had made measurements 

 of respiratory rate on Arbacia eggs confirming Warburg's work, these 

 seem never to have been published, so that the calculation could not 

 be more than an interesting feeler. Using Shearer's figure for oxygen 

 consumption (bearing in mind that it was obtained on Echinus, not 

 Arbacia) and Rogers & Cole's figure for heat-production, the calorific 

 quotient for the fertilised eggs (ist hour) worked out at 3-8, not 3-215, 

 and for fertilised eggs (2nd hour) at 3-7, not 2-37. Similarly, for the 

 unfertilised tgg, the calorific quotient worked out at 3-51, not 3-13 

 or 3*07. When these values are placed beside the older ones of 

 Meyerhof and Shearer, as in Fig, 117, it can be seen that they over- 

 pass all the theoretical levels just as the earlier figures failed to 

 reach them. There may be some significance in the fact that the 



