The page between 12 and 13 was lost, it's completed but not added due to a plot changes. Two more boys were also planned, along with LaSalle at the party, but due to the artist's health at the time, this idea was scrapped.
An excellent story, and I appreciate the extra art and additional information, but the page currently on page 14 (the one you identify as "the page between 12 and 13) is jarring in the gallery's current order. It confuses the reader, and makes the sequence of events seem illogical. I suggest it would better serve the gallery to put it at the very end.