Joseph Jongen is a Belgian composer (1873-1953), roughly contemporary of Vierne.
In these two small and concise pieces, one can find the typical characteristics of Jongen's melodies and harmonies, as they are better known in larger organ (and non-organ) pieces as Symphonie concertante, Chant de May, Menuet-scherzo, etc.
The Scherzetto is a witty mendelssohnian piece in a "Midsummer night dream mood". The central part is characterized by a beautiful (IMHO) singing melody. Its atmosphere has something of the 2nd movement of the symphonie concertante (Divertissement), but with much smaller dimensions.
The Petit prélude (also called Aria) is in pastoral mood and could remind some old popular tune.
It was written as a sight-reading test for organ exams at the Brussels Conservatoire.