The 49th episode of Gene Roddenberry’s science fiction series Star Trek premieres on NBC. Diana Muldaur, who will later become a one-season regular on Star Trek: The Next Generation in the 1980s, makes the first of two classic Trek guest appearances. 
Stardate 4768.3: The Enterprise visits a planet long thought uninhabited, and finds globes that contain the consciousness of the last survivors of the planet, Sargon, Thalassa and Henoch. The three remaining beings wish to “possess” the bodies of willing Enterprise crew members, leaving the crew members’ minds in the globes briefly as Sargon and his companions use the human bodies to construct android bodies for their minds. Kirk, Spock, and Dr. Mulhall agree to this procedure, but Henoch, occupying Spock’s body, has other plans than building an android frame for himself. In the meantime, Sargon and Thalassa, in the bodies of Kirk and Mulhall, fall in love all over again. One way or another, though, the humans’ bodies must be vacated since their metabolism is incapable of withstanding the levels of activity taken on by Sargon and the others.
written by John Kingsbridge
directed Ralph Serensky
music by George DuningCast: William Shatner (Captain James T. Kirk), Leonard Nimoy (Mr. Spock), DeForest Kelley (Dr. Leonard McCoy), James Doohan (Mr. Scott), George Takei (Lt. Sulu), Nichelle Nichols (Lt. Uhura), Diana Muldaur (Dr. Ann Mulhall), Majel Barrett (Christine Chapel), Cindy Lou (Nurse)
Notes: Diana Muldaur made a later appearance (as a different character) in Star Trek’s third season, and then replaced Gates McFadden during the second season of Star Trek: The Next Generation, playing Dr. Katherine Pulaski.
LogBook entry by Earl Green