Are Jekyll and Hyde the same person?
Yes. Hyde is the bodily identity produced when Jekyll's potion gives independent expression to impulses he has separated from his public self.
Why does the potion stop working reliably?
Repeated use strengthens Hyde, involuntary transformations begin, and the original salt apparently contained an unknown impurity that later supplies cannot reproduce.
Who is dead in the laboratory?
Hyde is found wearing Jekyll's oversized clothes after taking poison as Utterson and Poole force entry.
What happens to Jekyll?
His confession ends as Hyde is overtaking him and the last effective dose is failing; the body found afterward establishes that Jekyll cannot return.
Themes and What the Ending Means
Duality: The experiment literalizes conflicting desires that already coexist within one person.
Repression and indulgence: Jekyll's secrecy does not eliminate appetite; it creates a protected identity in which appetite can grow.
Respectability: Wills, reputations, locked houses, and professional silence protect the conditions in which Hyde operates.
Addiction and habit: Jekyll repeatedly claims control while his voluntary returns to Hyde make later compulsion possible.
Testimony: Enfield, Utterson, Lanyon, and Jekyll provide nested accounts that move the story from rumor to witnessed impossibility.