The Erlenmeyer Flask

"The Erlenmeyer Flask" is the 24th episode and the first season finale of the science fiction television series The X-Files. Written by executive producer Chris Carter and directed by R. W. Goodwin, the episode continues with the mythology story arc which started with "Pilot". The episode first aired in the United States on the Fox network on May 13, 1994. With 8.3 million households tuning in during its initial broadcast, the episode was the most-viewed episode of the show's first season. The episode received an Edgar Award nomination in the Best Episode in a TV Series category, and has, since broadcast, received positive responses from both critics and crew members.

The show centers on FBI special agents Fox Mulder (David Duchovny) and Dana Scully (Gillian Anderson) who work on cases linked to the paranormal, called X-Files. In this episode, Mulder and Scully discover evidence of secret government experimentation with alien DNA, but the evidence and all of the people who have seen it are promptly identified, located and targeted for elimination by men who are later identified as clandestine operatives.

"The Erlenmeyer Flask" introduced several new plot elements which would continue in later seasons and featured the death of recurring character "Deep Throat" (Jerry Hardin). Carter described the inspiration for the episode as "the result of a year-long learning experience".