The Energy Sources in Ontogenesis

Abstract

1. Experiments have been made upon the oxygen consumption, CO2 content, and respiratory quotient of the eggs of Limnaea stagnalis, the common pond snail. 2. Throughout the period of development, during which accurate determinations are possible, the mean value of the R.Q. was 1.05. The significance of the observations is discussed in the text, the main conclusion being that fat is synthesised in the course of development. This was confirmed by extraction of the ether-soluble substances. 3. Preliminary experiments upon the nitrogenous metabolism show that uric acid is synthesised by the embryo during the latter part of development, but suggest that protein does not constitute the source of the synthetic fat.