“DNA Mad Scientist” is episode nine of season one of Farscape.
The crew are visiting a scientist who has maps of substantial areas of the galaxy and can pinpoint their homeworlds using their DNA.
In exchange for maps, which will allow them to get home without meeting the Peacekeepers, who wants a price – genetic material from the Pilot. Not just a small sample, but an entire arm. Admittedly, Pilot has several, but they take it without his permission. Fortunately, he can grown them back. He’s still not happy. This decision causes a lot of problems.
Unfortunately for Crichton, Earth wasn’t in the database.
The mad scientist comes complete with an Igor (or an equivalent), so he is obviously up to no good.
Bit of a morality episode, as it shows what levels the crew are willing to stoop to to accomplish their ends.