 Instead, he took his discharge in Manila and, under the auspices of the Field Museum, organized a major biological expedition into the interior of the Philippine islands of Mindanao and Palawan (1946-1947) and spent the next two years exploring and collecting in those biologically poorly known islands.The collections resulting from his efforts were the richest ever made from those portions of the Philippines.Following his return from the Philippines in 1948, he joined, as an employee of the United States Navy Bureau of Medicine and Surgery, the University of California African Expedition in 1948–1949.