The corals that form the structure of the great reef ecosystems of tropical seas depend upon a symbiotic relationship with algae like unicellular flagellate protozoa that are photosynthetic and live within their tissues.

In 1932, he finished his PhD and, with the help of a grant from the Rockefeller Foundation, moved to the Kaiser Wilhelm Institute for Medical Research of Heidelberg to Otto Meyerhof, where he did research on the development of flagellates.