Here's the very FIRST Tarzan movie, released just six years after the novel appeared in All-Story Magazine. This film, which portrays the first half of the novel (concluded in the 1918 movie The Romance of Tarzan) is said to be the most faithful of all the screen adaptations.
The ERBZine website has a lot of great info HERE. Among other things, it says:
NFC (National Film Corporation) hired eight acrobats to play apes for which costumes made from goat skins and elaborate masks were constructed. Additional ape costumes were made in Morgan City and twenty Young men from the New Orleans Athletic Club were hired to augment the "apes" brought from California
On with the show!