 During World War I, he served with the Highland Light Infantry and as a captain in the Royal Flying Corps.After completing his PhD he held posts at the Institute of Agricultural Parasitology, London (1923-1925) and the London School of Hygiene and Tropical Medicine (1925-1932).In 1932, he emigrated to Canada to assume the position of Professor of Parasitology, and was appointed the founding director of the Institute of Parasitology at Macdonald College, McGill University.