Shortly after he was promoted to a research assistant from a drawing technician at the botanical laboratory of Imperial University of Tokyo, he showed to associate professor Seiichiro IKENO, spermatozoids of ginkgo, which he found but mistook for some parasite worms.
平瀬は、当時東京帝国大学の植物学教室の画工から助手になってまもなく、寄生虫かと思って当時助教授だった池野成一郎に見せた。