I remember a scene in The Swiss Family Robinson where the young boy is bitten by a spider (the web has come up out of nowhere) and the father sucks out the venom and gouges out the wound with a knife before it can harm him.  A very scary scene, but it was interesting that I understood what he was doing almost immediately, without having any knowledge or expectation that this was something you could do.

This is another of the earliest movies I remember, and that I associate with the large-screened Upper West Side theaters I saw them in.  The juxtaposition of the large, somewhat threadbare theater and its smells with the slightly underlit movies you saw there is something that I am only conscious of now.  They may feel underlit (now: this was natural then) because when I was little we went during the day.  Or they may seem underlit as I remember them in comparison to today's bright flat screen TVs.  (I recollect The Planet of the Apes as underlit as well, though I remember seeing it much later in my childhood.) But that was fine -- the movie world seemed all the realer in being both very large and somewhat distant from the crowd in the grungy theater.