In panels 7.7 to 10.2, the laboratory mouse blackmails Scrooge by threatening to destroy a 10.000 Euro bill. This freely resembles the part of Barks' idea, in which Scrooge is blackmailed by a rat, which threatens to destroy a $10.000 bill:
The rat gets in (by gag means) and then begins a battle of personalities between him and Scrooge. Scrooge corners the rat, and is going to shoot him, but the rat picks up a big bill and holds it in front of him for protection. Scrooge cocks the gun. The rat looks at the denomination of the bill, throws it away, and grabs a bigger one. Scrooge sights down the gun barrel, sees the figure $10,000, and goes chicken.
He can't shoot a ten-thousand dollar bill to pieces, so he clubs the gun, poises to clonk the rat, but the wily rodent sticks the bill between his teeth and threatens to bite it if Scrooge gets tough. Scrooge is stymied. The rat senses the tremendous power the possession of this bill gives him over Scrooge. He merely has to gesture that he wants cheese, and Scrooge hastens to order him some.
But the rat overuses his power. He makes Scrooge bring him cheeses after cheeses, the choice of Roqueforts, Camemberts, fine Swisses, all of which he refuses as being too cheap for his refined tastes. Scrooge finally has to order the most expensive cheese in the world, ODORA DE PUNGENTO, which is brought from its mountain cave in an armored car, and served to the rat on a velvet cushion accompanied by a flourish for trumpets. This satisfies the rat. He prepares like a gourmet to eat this fine cheese in style.
Scrooge gets his adding machine, adds up how much all this is costing him. So much for the cheese, so much rent for the armored car, rent for the velvet pillow, fee for the trumpeteers, etc. It totals ten thousand dollars and ONE CENT! He snatches the cheese from under the rat's nose. "Take it back," he says to the cheesemen. "It's cheaper to let him eat the money.
Scrooge goes berserk. Spouting duck talk, he routs the rat, who goes back to his garbage can, glad to escape with his life.
According to what survived of Barks's idea, Donald only appeared at the beginning and the end of the story, with little or no interaction between him and Scrooge. This lack of interaction is believed to be a problem in Barks's idea, at least in Thomas Andrae's and Geoffrey Blum's article «The Animated Scrooge», published in the The Carl Barks Library - Set IV (04B-459). In Jippes's version, there is a lot of interaction between Donald and Scrooge, and they stay together throughout the entire story.
In Barks's idea, the plague of rats is introduced when Scrooge turns on the radio, just before his frugal lunch of crackers and cheese. Jippes's approach has two steps. His story starts with a plague of mice, and then the radio announces an additional problem: the escape of intelligent laboratory mice.
With the radio announcement, Jippes explains the intelligence of the mouse. What survives of Barks's idea doesn't give any explanation for the intelligence of the blackmailing rat.
In Barks's idea, Donald operates a money-sorting machine that runs by power. In Jippes's version, Donald operates a bulldozer (panels 1.1) and a security system (panel 2.2), but the money-sorting machine is omitted.
Barks ends with Scrooge being bilious and hiccupy, drinking a bicarbonate of soda. Jippes ends with Scrooge feeling good about his battle against the mouse, because the victory was just what Scrooge needed.
In «in "Only a Poor Old Man"», Scrooge is
fighting against rats, a spider, and moths. After a while, Scrooge is caved
in. Donald phones his nephews for help to take care of Scrooge. He also asks
them to bring a sandwich, because he bets the old tightwad hasn't had time
to eat for a week.
In Jippes's story, Scrooge is fighting against rats and spiders. Scrooge's treatment of the burglar alarm with the cobwebs
According to «in "Only a Poor Old Man"»,
Scrooge has a trick for diving into his money without getting hurt