The eminent Bulgarian plant geneticist Dontcho Kostoff wrote to Muller to share with him what details he knew. Kostoff's own career would be destroyed by the Lysenkoist (Michurinist) movement in communist Bulgaria in 1949.

The Seventh International Genetics Congress that Vavilov had desperately hoped Muller could bring to the USSR followed Muller to Edinburgh instead. In a symbolic gesture, an empty chair on the podium was left for Vavilov, the elected chairman of the Congress, during the opening ceremony. The large Soviet delegation, planning to present some fifty papers, was forbidden to attend due to the continued politicization of genetics research in the Soviet Union.

The Congress came with all the anxieties one would expect of an international gathering on the eve of a world war. Many papers were read in absentia, delegations had to leave suddenly, and the conference was concluded early. Several delegates sought to return home on the transatlantic British passenger liner SS Athenia, which, tragically, was confused for an armed vessel and torpedoed by a German U-boat hours after the declaration of war. There were 118 casualties, including an American geneticist and his wife.

The statement can be seen here with Muller's introductory note to the journal editor.

The last communication between Muller and his close friend the Russian geneticist and explorer Nicolai Vavilov.

In response to Nazi eugenics and other terrifying movements that claimed to make use of genetics, Muller drafted, and 22 other geneticists signed, the “Geneticist’s Manifesto.” The formal statement highlighted the relevance of genetics (and eugenics) to human well-being, but attacked the racist and dehumanizing tendencies of much of eugenics. Muller sent a copy of the manifesto to Vavilov. His response is the last of their communication.