I've been trying to watch these Tarzan movies in more or less chronological order, but somehow I missed Tarzan's Revenge from 1938. Now I wish that I'd kept right on missing it.
It's a typical Tarzan plot: a bunch of civilized folks come to the jungle to trap animals and get in trouble, so Tarzan has to save them. In this case, the civilized folks are the Reed family: bumbling Dad, complaining Mom, and pretty Eleanor. They've also brought along Eleanor's cowardly husband Nevin who likes to shoot crocodiles from the deck of a riverboat, but gets creeped out if a chipmunk runs across his foot. Actually, Nevin's the best part of the movie. His weaseliness is at least funny.
The conflict comes in when a wealthy sheik decides to add Eleanor to his harem and plots to have her party captured and brought to his jungle palace. Fortunately (I guess), Tarzan encounters the party and falls for Eleanor, ensuring his protection against the evil sheik.
Putting aside for a second the problem with Tarzan's falling in love with anyone besides Jane (who's not in the movie), there are lots of other problems to look at. Glenn Morris isn't a handsome Tarzan, but he also must not have been much of an actor either. He has maybe three lines in the entire movie and they all consist of his pointing to himself and saying, "Tarzan." He was obviously hired due to his being an Olympic athlete and he never played Tarzan (or any other character, for that matter) again.
The movie's only a little over an hour long and most of it is filled with fluff like Tarzan's goofing around in the jungle with his unnamed chimpanzee pal. Tarzan comes across as a Peter Pan type figure who spends his days loafing, swimming, and getting into mischief. When he first encounters Eleanor, she's stuck in a mud pond and he briefly rescues her before playfully tossing her back in.
Of course the plot requires that Eleanor still fall in love with Tarzan even though he's a big jerk, so she does. There's absolutely no chemistry between the two of them though and it's completely unbelievable when she decides to stay with him at the end of the movie. Oops, I've spoiled it for you. You're welcome.