The above scan is of the illustration of a one-page story about Disney's first tv test, in which the Big Bad Wolf makes a last moment appearance, published in vol. 4 no. 8 of Mickey Mouse Magazine, dated May 1939. This short story is very interesting for being a relic of a precise moment in history where this new medium was still largely unknown to the larger portion of the population and yet was on the verge of kick-off.
The story starts with Walt Disney calling on all the Disney characters to attend a "television test". Mickey is clueless as to what that means and Minnie even speculates that they are being summoned to a check-up of their eyes! However, Clara Cluck who had "picked up no end of gossip" clears up the "mystery":
"Why haven't you heard," she clucked. "Everyone is talking about this wonderful machine. It takes your picture just like a camera, a movie camera, only it travels through the air."
A short overview of the history of television in the US is necessary for putting this story in perspective. While limited television service had technically started in the US as early as 1928, these low-def broadcasts had not become widespread beyond experimental stations run by universities. Only after 1936, when hi-def broadcast became possible, did the new medium really began to get kick-off. NBC, which had began regularly scheduled broadcasts on April 30th, 1939, aired Donald's Cousin Gus on May 19th, making it the first film cartoon to be televised in the US. Hence, the short story covered in this blog post was published on the eve of this historic event.
Source on history of tv in the US: wikipedia