The history of the discovery of vitamins was the history of their deficiency disorders. Casimir Funk, the father of vitaminic therapy, studied the interrelationships in the human body of those elements that Christiaan Eijkman demonstrated in animals, particularly birds. In 1911, he designated these factors vitamins (vita = life and amine, a nitrogenous substance essential for life); this name was accepted by the scientific community in 1912. Here, we intend to give an illustrative view on the early days of vitamin research as carried out by Casimir Funk.