In collaboration with my assistants, O. Ulvesli, M. Husby and K. Breirem, I have been working for the past 7–8 years with problems as to the vitamin requirement of calves, young cattle and growing pigs. The purpose of my investigations was to discover, if possible, the practical significance of the vitamin hypothesis in its bearing on agricultural practice. It is a well-known fact that the indiscriminate application to farm animals of results obtained with small laboratory animals is not warranted—the requirements of each species of animals must be tested separately. As a starting point it was necessary, therefore, to consider first, whether or not farm animals exhibit the same susceptibility to vitamin deficiency as the small laboratory animals, and secondly, whether or not our commonly used feeding stuffs for farm stock contain enough vitamins to avoid any deficiency symptoms.