Abstract
1. Concerning the growth-stimulating effect of fresh beef liver on rainbow trout fingerlings, the metabolism of ingested amino acids in the liver was studied and successively the occurrence of vitamin A-protein-complex in the liver was tested by electrophoresis, but no positive results were obtained.
2. Halver's vitaminological aspect of fresh liver as a high vitamin diet was investigated but no possible confirmation could be obtained.
3. The enzymatic fractionation using sucrose was tested and the fraction soluble in 45 per cent sucrose solution was found most effective as the growth-promoting factor for rainbow trout fingerlings. Repeated investigations showed that the active principle of fresh liver for the fish fingerlings might be chiefly due to various vitamin-dependent enzyme systems.
