Glen Corbett guest stars as Zefram Cochrane, the inventor of "space warp", in this ambitious episode based on the idea of infinite diversity in infinite combinations. Written the same year the . Supreme Court forced 16 states to abolish their anti-miscegenation laws, the idea of a romance between Cochrane, from Alpha Centauri, and an incorporeal entity, from a distant planet, pushes the boundaries of the issue so effectively, it demonstrates just how silly it is to stop two Earth people from loving each other.
One of the few second season episodes not to be directed by Joe Pevney or Marc Daniels, "Metamorphosis" is a planet-based adventure that takes advantage of wide angle lenses and new colors to show off a new look. (There are even clouds in the sky, thanks to the crew pumping them in through the air vents!). Enhancing the visuals, George Duning supplies the episode with the most sensitive score of the series, providing cues that reappear throughout the remainder of the series.
Unfortunately, Cochrane, himself is rather wooden. Corbett does what's asked of him, but the result is a character that comes across as an office worker putting in late night, not someone stranded on an asteroid for over a hundred years. The irony is that if Cochrane were to appear more wild and unhinged, it would not only add interest to his performance but enhance his alien nature. (After all, if he's going to appear a regular guy, why not just have him be from Montana and make him the inventor of warp drive for Earth as opposed to the galaxy?)
Cochrane shares the stage with the incorporeal being known as "the Companion", effectively brought to life by both a special effect and (thanks to the introduction of the Universal Translator) the voice of Elizabeth Rogers (the same actress who substitutes for Nichelle Nichols in "The Doomsday Machine" and "The Way to Eden"). Rogers, who was hastily chosen as the Companion's spokesperson after the first choice gave a poor performance, gives the creature a spring-like innocence that goes well with the Duning's music, turning the story into one that's easy to empathize with. (There's also Elinor Donahue, the eldest daughter from Father Knows Best, playing a Federation Ambassador, but she's really just there to serve one purpose, which becomes clear near the end).
In a way, "Metamorphosis" is the second season's version of "Devil in the Dark", with Coon once again using a sci fi communication device to show us that just because something is different and scary doesn't mean it's evil and without feelings. (Coon's teleplay also includes the notion that male and female genders are universal concepts, an idea probably there just to make the episode's relationship more acceptable to families of the 1960s. Unfortunately for Coon, the concept isn't even true on Earth, and it's rightly abandoned by future Star Trek
Interestingly, the idea of an alien creature falling in love with a person and merging with another person to consummate the relationship returns in Star Trek: The Motion Picture. Zefram Cochrane himself returns in Star Trek's eighth motion picture, First Contact, where he's reinvented as a guy from Montana who's merely the inventor of warp drive for Earth alone. (This, of course, makes a name created for someone from Alpha Centauri a very unusual name for someone from the Earth. But I suppose having the series set hundreds of years in the future gives it an advantage, since you can argue the name will come into fashion later
Taken literally, "Metamorphosis" might not work within the mythology Star Trek develops, taken figuratively; it's a landmark episode and has some interesting things to say.
Remastered: Like "The Galileo Seven", the shots of the shuttle in space get a major upgrade, including the final shot of the episode which (replacing a stock shot of the Enterprise) shows the shuttle departing the asteroid to approach the Enterprise. The asteroid itself (originally a reuse of planet from "Mirror Mirror") is turned into a much more colorless world, which befits its nature but doesn't tie in as well with the purple sky we see on the surface. CBS does, however, touch up the surface stage set, digitally removing strategically placed rock formations that had to be used in the original shoot to disguise the edges of the set. And while Kirk's ship doesn't appear until the second half of the episode, there are, of course, new shots of the Enterprise.