I'm trying to figure out how viewers in the 1960s would've understood the Federation. So far as I can tell, there's nothing in the first season that indicates the Enterprise is part of a multispecies confederation. Sure, Spock is in Stafleet, but as a half-human he could simply be an exception in the same way that Worf's presence on the E-D doesn't mean the Klingons are part of the Federation. All the planets the Enterprise visits in season one are either aliens outside the Federation, or human colonies within it, which leads me to believe that a viewer in summer 1967 would've assumed the Federation was simply Earth and its colonies. Can anyone think of a reference that I'm missing that would've established the multispecies nature of the Federation in the first season? And if not, when was it introduced? "Journey to Babel"?