In late 1920s von Neergaard identified the function of the pulmonary surfactant in increasing the compliance of the lungs by reducing surface tension. However the significance of his discovery was not understood by the scientific and medical community at that time. He also realized the importance of having low surface tension in lungs of newborn infants. Later, in the middle of the 1950s, Pattle and Clements rediscovered the importance of surfactant and low surface tension in the lungs. At the end of that decade it was discovered that the lack of surfactant caused infant respiratory distress syndrome (IRDS).