Studies in the Development of the Rainbow Trout (Salmo Irideus)

Abstract

1. The total carbohydrate content of the trout egg and embryo has been measured. The carbohydrate content falls during three periods: (i) the establishment of the blood circulation; (ii) hatching; and (iii) the onset of starvation. 2. The fats extracted by a non-polar solvent (carbon tetrachloride) from egg, embryo and yolk samples show no significant catabolism before hatching. These fats are considered to be glyceride-fats. In the yolk-sac stage such fats are only consumed between the 63rd and 80th days of incubation at 10°C. 3. The combustion of phosphatide fat deduced from the heat-production figures is conspicuous during the early stages of yolk-sac absorption, and may be correlated with the consumption of protein as an energy source. 4. These findings may be correlated with histological changes in the yolk-sac wall, and in the relation between yolk-sac and liver. The concept of a sequence of energy sources in ontogenesis is discussed.