ABSTRACT
The class of compounds used by the developing embryo for the extraction of energy from its environment raises one of the most important questions which arises in the biochemical analysis of embryological phenomena. Does it behave exactly like the adult animal from the very beginning, or does it pass through phases each of which are, in this respect, different? To be able to compile a chart showing the compounds which the developing embryo utilises as energy-sources throughout its ontogenesis, to know the times and periods in which one supersedes another, would be to possess clues of enormous importance for the unravelling of every event in embryonic metabolism.
Moreover this figure is low, if anything, for the glycogen disappearing at the same time as the glucose has not been taken into consideration.
