Whistler and his Jug Band

Whistler and his Jug Band - Low Down Blues (1927)

Can someone please explain what the fuck is going on on this record? I guess I shouldn't be so surprised that you can bend notes like that blowing a jug, but what is that theremin-sounding instrument? If I were guessing, I'd say it was someone playing a saw, but liner notes list guitar, fiddle, mandolin, jug and NOSE WHISTLE. The latter is played by Whistler himself (he also sings and plays guitar on this track, real name Buford Threlkeld). Found on this nifty compilation.