My friend sent me a bunch of Life Magazine articles by RCB and "A Polyp with a Past" was one of them, I suppose predating the script for the film, "Sex Life of a Polyp."
The Robert Benchley Society responded:
According to Gordon Ersnt, in Robert Benchley: An Annotated Bibliography (page 39), "Polyp with a Past" first appeared in Life of December 22, 1921. The film "Sex Life of a Polyp" (see Ernst page 202) dates to July 25, 1928 and is based on the essay above and on "Do Insects Think?" (Life, August 3, 1922) and "The Social Life of the Newt" (Vanity Fair, December 1919).
The RBS has on its website a List of Benchley Essays with which Books They Appear In which shows the following:
"Polyp with a Past" appears in Love Conquers All (1922) beginning on page 92 and Benchley Beside Himself (1943) beginning on page 1.
"Do Insects Think?" appears in Love Conquers All (1922) in beginning on page 62 and Benchley Round-up (1954) beginning on page 44.
"The Social Life of the Newt" appears in Of All Things (1921) beginning on page 3, Inside Benchley (1942) beginning on page 1, and Benchley Round-up (1954) beginning on page 11.
Love Conquers All is in the public domain in the United States and is available on the RBS website at http://www.robertbenchley.org/lca/index.htm.