This cartoon has stuck with me all my life. I've even drawn upon it as a classroom teacher. The essential brilliance is the contrast between the two menaces. As Sniffles and the bookworm wander about the toy store, they are stalked by the store's cat. But when they turn a corner, they are threatened by the mechanical duck. The cat is rational: it wants to kill and eat. It's dangerous, but it has a motive, and thus there's a certain predictability to it that can be used to evade or defeat it. The mechanical duck, on the other hand, is entirely irrational, therefore unpredictable. In "real life" it would be the familiar child's pull toy. But Jones portrays it from a low angle, so that it looks huge. I always found it very scary.