Fat metabolism in fishes

IN a previous communication [Lovern, 1932, 2] data were given of the fatty acid compositions of the glycerides from three dep6ts in a single fish (Acipenser sturio), and some evidence was adduced that a reversible change from palmitic into palmitoleic acid was one factor controlling depot fat composition. It was also suggested that for the sturgeon the fat in all depots required a constant ratio of saturated to unsaturated acids. Three other species have now been studied, the conger eel (Conger vulgaris), a dolphin (species unfortunately not determined with certainty), and a porpoise (Phocaena communis). In the case of the conger eel, the main fat depot consists of two strips of adipose tissue attached to the peritoneum, whilst the liver is a subsidiary depot. In order to obtain sufficient liver fat for a full analysis, twelve large fish were used, the peritoneal fats and liver fats being combined. In the case of the dolphin (an immature specimen) and the porpoise (an adult female with a well-developed foetus) the main fat depot is the blubber. This was divided into two classes in each case; (a) that from the body, and (b) that from the head, which is mainly found in a thick deposit in a hollow of the skull. These two fats had different compositions. In addition, the jawbones of these animals are filled with an oily pulp, which was extracted, giving a fat of different compositiori from the blubber fats.