Carolina H. MacGillavry: the first woman in the Royal Dutch Academy of Sciences; on the beauty of crystals, female intuition and a flexible mind Carolina H. MacGillavry (1904-1993) made her career in chemical crystallography in the University of Amsterdam. She already wrote some major works in this field in collaboration with Jo Bijvoet, her male tutor and friend, before World War II. After the war, she visited the United States where she worked with Ray Pepinsky. From their correspondence it becomes clear that Pepinsky thought her to be too modest - and judged this to be a feminine problem - for not presenting all her findings; she herself did not want to publish her work before she was quite certain on all its aspects. Because of this prudent manner she did not get as much praise for her findings on the Harker-Kasper equations as did her colleague Jerome Karle who received the Nobel prize in this field. At the age of 46 she became professor in crystallography and the first woman to be elected member of the Royal Dutch Academy of Sciences. Emerging from the school of the crystallographer William Lawrence Bragg, she herself gave rise to a generation of female 'descendants' in the 1960's and '70's. This female heritage did not last until these days. Her career reveals the conditions that favoured a woman's vocation in the middle of this century: superiority in her field of research, unmarried so without personal obligations and with the support of male colleagues.