Heinkel wrote in his memoires ‘Stürmisches Leben’ (stormy life) (cited after the special edition of the Europäischer Buchlub, page 199-200):

For the summer of 1932 an ‘international contest’ was advertized, the third of its kind. I decided, to build for the first time an aircraft, which should get the most modern aerodynamic line in our conception. For the time being, I wanted to build this aeroplane in wood. She got the designation He 64, and attracted attention with a unusually slim, well shapeed fuselage of an oval cross-section and a cabin, which was covered by a completely closed, aerodynamically efficient Cellon-canopy. The relatively light engine of 150 horsepower has been cowled, that it integrated with the whole aeroplane.
The wings were cantilevered and as flush as possible covered with plywood. Modern slots ensured a slow landing speed. I did not take the step to a retractable landing gear.
Painted red, as ‘Red devil’, this He 64 became a first aerodynamic upset, which the subsequent airforce-general Hans Seidemann in august 1932 made famous with exceptional stage wins on the international circuit of the european tourist plane contest. He provoked a storm of applause, when the aeroplane at the evening of the latest day of the competition, the 27th august 1932, racy like an arrow, landed in Berlin-Staaken.
Seidemann needed for the distance of 7500 km, for which a flying time of 6 days had been provided, only 3 days. On the first leg, which lead from Berlin via Warsaw, Praha and Vienna to Rome, he had left all the others behind. He had beaten especially the Italians, who provided their best machines, to be the first in their capital. It had become a dedicated competition between the Italian Colombo and Seidemann.
But Seidemann landed with my ‘Red Devil’ with wide margin as the first in Rome. On the next morning, he started to the second leg, via Florence, Nice, Lyon, Stuttgart and Bonn to Paris. At the evening of this day nobody in Paris expected, that one of the competing aeroplanes would arrive. The airport employees in part were already at home, when at the sky the noise of a fast approaching aeroplane became audible. Seidemann landed with the ‘Red Devil’. That was not experienced before. The press-people alarmed on the same evening their newspapers in whole Europe. But this was not the end. Seidemann resolved to also make the last leg from Paris via Amsterdam, Copenhagen, Goeteborg and Hamburg to Berlin in one day. He also accomplished that.
The applause of the convened crowd did indeed know no bounds.