I first found this posted by Duke Hayes in alt.humor.puns.
Jim Finn, the noted biologist, was stumped. He had spent months studying the little green frogs in the Keefo swamp. Despite all efforts at predator control, the population was declining at an alarming rate. Finn finally went to the chemistry department at his college to see if anyone there might be able to help. Tom looked into the problem and came up with a solution. The little frogs had succumbed … Read the rest...