CME de Oliveira's blog), Hawthorn seems to be obsessed with hands:
1) The birthmark in the story of the same name is in the form of a hand. When it is gone from the cheek of the scientist's wife, life flows away from her.
2) A poisonous mark of the Rappacini's daughter's hand is left on the skin of her not-yet-lover after she touches him, trying to stop him from approaching the poisonous flowers. He is infected through this mark as well as through her breath, as she never touches him anymore.
3) The butterfly in The Artist Of the Beautiful seems to be "working" only from one's hand, and it somehow feels the person's personality through the hand.
Those hands fascinate me even more than eyes in Poe's stories. A hand seems to represent life and to be connected with the soul both as a representation of its disposition and means of reaching and contaminating it.