656 THE RESPIRATION AND [pt. iii 



and in this he confirmed Meyerhof's findings. He therefore con- 

 cluded that only a negligible quantity of the energy liberated in the 

 high metabolic intensity of the fertilised egg-cell was expended in 

 bringing into being the visible morphological structure of the embryo. 

 It was employed, he thought, in keeping the living substance 

 itself intact as a physical system. Energy used for this purpose 

 would presumably come under the heading of developmental work 

 or "Entwicklungsarbeit", and this problem will be fully discussed 

 in a succeeding section, but it may be said here that all the 



Table 78. 



Heat-production in gm. cal. per 

 gm. dry weight per hour 



evidence goes to show that it is very small proportionately to the 

 general energy turnover of the embryo. At the same time, it 

 remains a remarkable fact that the calorific quotient of the early 

 stages of echinoderm development, at any rate, should be exactly 

 the same no matter whether morphological differentiation is pro- 

 ceeding or not, i.e. before fertilisation and under phenyl-urethane, 

 as against normal development after fertilisation. All these facts 

 together with others which have been referred to above go to show 

 the comparative independence of processes collaborating simul- 

 taneously in embryonic development to produce the finished organism. 

 The developmental mechanisms do not function at the same rate 

 or with the same rhythm, and the great problem of the future is 



