Freshening up lettuce

I learned this from a produce guy at the grocery store.  In Wisconsin in winter, our lettuce from California can use a little sprucing up.  I slice off the bottom (1/2" maybe?) of the lettuce head and put it in a bowl with water just to cover the bottom, cover with a plastic bag and refrigerate.  One day later, the lettuce head is considerably larger and the leaves are crispy!  Can you tell which is which from these pictures?