the crews were read a statement from Soviet Premier Leonid Brezhnev, and received a phone call from U.S. President Gerald Ford. While the two ships were docked, the three Americans and two Soviets conducted joint scientific experiments, exchanged flags and gifts (including tree seeds which were later planted in the two countries), listened to each other's music (examples include "Tenderness" by Maya Kristalinskaya and "Why Can't We Be Friends?" by War), signed certificates, visited each other's ships, ate together, and conversed in each other's languages. (Because of Stafford's pronounced drawl when speaking Russian, Leonov later joked that there were three languages spoken on the mission: Russian, English, and "Oklahomski".) There were also docking and redocking maneuvers, during which the two spacecraft reversed roles and the Soyuz became the "active" ship. American scientists developed four of the experiments performed during the mission. Embryologist Jane Oppenheimer analyzed the effects of weightlessness on fish eggs at various stages of development. After 44 hours together, the two ships separated, and maneuvered to use the Apollo to create an artificial solar eclipse to allow the crew of the Soyuz to take photographs of the solar corona. Another brief docking was made before the ships went their separate ways. The Soviets remained in space for two more days, and the Americans for five, during which the Apollo crew also conducted Earth observation experiments. Re-entry and aftermath The mission was considered a great success, both technically and as a public-relations exercise for both nations. The only serious problem was during reentry and splashdown of the Apollo craft, during which the crew were accidentally exposed to toxic hydrazine and nitrogen tetroxide fumes, caused by unignited reaction control system (RCS) hypergolic propellants venting from the spacecraft and reentering a cabin air intake. The RCS was inadvertently left on during descent, and the toxic fumes were sucked into the spacecraft as it drew in outside air. Brand briefly lost consciousness, while Stafford retrieved emergency oxygen masks, put one on Brand, and gave one to Slayton. The three astronauts were hospitalized for two weeks in Honolulu, Hawaii. Brand took responsibility for the mishap; because of high noise levels in the cabin during reentry, he believes he was unable to hear Stafford call off one item of the reentry checklist, the closure of two switches which would have automatically shut off the RCS and begun drogue parachute deployment. These procedures were manually