Nirvana 'In Utero' Reissue Features New, Unreleased Songs 'Forgotten Tune' and a 'Jam,' Three-Disc Collection Includes Live DVD [VIDEO]

Nirvana's 20th anniversary reissue of their final studio album "In Utero" is set to hit shelves on Sept. 24. Fans of the legendary grunge rock group have been speculating for months about what rarities will appear on the upcoming release.

Unlike the "Nevermind" rerelease that was issued in 2011, the "In Utero" compilation includes over 40 new demos from the "In Utero" era of the band's career, according to Rolling Stone.

As previously reported, the "In Utero" re-release contains three discs. Disc one will include the original album, mixed by Steve Albini and in its original form. The original B-sides and officially-recorded songs from the "In Utero" era will also be included on the first CD. This includes, of course, US bonus track "Gallons of Rubbing Alcohol Flow Through The Strip," the "All Apologies" B-side "Moist Vagina" and "Marigold," Dave Grohl's first ever solo song (considered by many to be the first Foo Fighters track).

The second disc is where things get notably more interesting. A 2013 mix of the album will comprise the first half. Though its unclear what exactly that indicates, it's likely it's a simple remaster, with fuller sound and different adjustments. Though everything on disc one is old fare, new demos will be unveiled with disc two.

The Rio and Word of Mouth sessions are the main source for the previously unheard material. Demos of "Very Ape," "Dumb," "Tourette's," "Pennyroyal Tea" and more will be released.

Most excitingly, though, are two previously unreleased Nirvana songs. "Forgotten Tune" is the second-to-last track on the second CD, and is reportedly an instrumental track. Another song, entitled simply "Jam" closes out disc 2, though that is likely just a fun jam-session from the "Smells Like Teen Spirit" band.

The third disc will be a live album, comprised of their MTV "Live & Loud" performance from 1993. A live CD will also come with the "In Utero" rerelease.