There’s an awful long set-up before we get to the transformation scenes in the MGM cartoon “Dr. Jekyll and Mr. Mouse” (1947). Tom spends over a third of the cartoon trying to keep his milk away from Jerry.
There are plot holes you can drive the proverbial truck through in this cartoon but there are still some fun things. Scott Bradley’s pounding music when the transformed Jerry stomps toward Tom sounds like anything but a Scott Bradley score. There’s a great use of colour (and shadow) in the scene where Tom’s mixing the poison. And there are the transformation drawings.
Ken Muse, Ed Barge, Mike Lah and Al Grandmain get credit on this. One wonders whether Grandmain, who I understand was an effects animator at one time, handled at least some of the transformation drawings. Here are a few after Jerry drinks the milk mixture. The brushwork is admirable.
And here’s the first time he changes back. Some drawings are simply brush lines to indicate Jerry, some are jagged heads, a few are full body drawings. The explosion at the end is interesting. A frame of solid colour (yellow, blue, etc.) is interspersed with an animation drawing.
Why a mouse likes milk in the first place, why the milk mixture didn’t turn the fly that drank it into a musclebound fly and how Jerry knew even the approximate formula recipe are questions you can ask yourself and ignore, because you’ll never get an answer. Enjoy the drawings instead.