What is a sad thing that happened to the Doctor in "Dr. Heidegger's Experiment"?

Dr. Heidegger is sad to discover that the wisdom of experience does not guide his guests after they drink of the elixir of youth. He's shocked to see these five supposedly mature individuals turning before his very eyes into juvenile delinquents after sampling a drop of his magic spring water.
The good doctor had hoped that his guests would draw upon their extensive life experiences and avoid what he calls the dangers of youth. He was sure he'd picked the right subjects for his scientific experiment, but he couldn't have been more wrong. Instead, he's profoundly disappointed by the childish behavior of his guests once they start to feel the elixir's intoxicating effect. Furthermore, the fact that he personally chose these people for his experiment doesn't reflect very well on him at all.