 David Duchovny (qv)s character Ira makes an incredible (and  ultimately, correct) leap of logic when he deduces that the element  selenium might be as poisonous to the alien life forms as arsenic is  to humans. Fox Mulder, Duchovnys character on  _"X Files, The" (1993)_ (qv), is notorious for arriving at similarly  implausible (and usually, correct) leaps of logic (usually just in  time to advance the plot prior to the commercial break!).