Where does Jekyll's beard go when he turns into Hyde?

I wondered this too. Apparently Jekyll has stumbled onto the formula for some arcane elixir that would be better suited to the supernatural.

Circa 2012, this formula would be hacked and reversed as a hair growth product and a billion dollar company.



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Although in the usual Stevenson plot, the good man becomes a hairy oaf with swollen features, in this case just the opposite occurs. So it shouldn't be hard to imagine the beard goes away when the man becomes "a man of this world." Rather like the man changing into a werewolf. Where does all that hair come from? It goes with the territory, so to speak.

"Cum Grano Salis"

The theme of the movie, corresponding to Dr. Jekyll's theories (in this version anyway), is that a person's superior self is caged within the individual, shackled by the constraints of societal rules and conventions. As such, he believed the caged person within is the more progressive. Thus Jekyll basically looks like a Neanderthal whereas Hyde looks and behaves like a "progressive" libertine.