This ad was part of a series that ran in Liberty Magazine, with a different cartoonist supplying the pitch for Wheaties breakfast cereal in each issue.
Virgil Partch has long been one of my very favorite single-panel cartoonists.
About a month ago I posted a small spotlight on his work, pointing out various places around the web where you can see more of it.
Click here to check it out and follow those links.
Since that post, there's also been a further installment of great cartoons from VIP's book, 'The Wild, Wild Women' posted at the ASIFA-Hollywood Animation Archive website. Go take a look at that, too!
See also: More info (and further links) regarding Liberty Magazine at Wikipedia.