A Major for July 26

Today’s P&F is the cheerful and memorable A major Prelude, followed by four pages of three voiced-fugue possessed of an unusual subject rising in fourths.  It seems like I should be able to find a retrograde or inverted subject somewhere in all four pages of the fugue, and, that with the fourths, it should be easy to locate.  But no, all the subjects I have marked rise resolutely in fourths, not the thirds which would indicate an inverted subject.  Perhaps someone out there has found a prized retrograde subject.  I’ve still never found one in the entire WTC.