It is ironic that Mr. Appin is killed by one of the animals he is working with, since working with the elephant was suggested as safer for people than having house cats and other household pets.
Irony is when something happens that is different from what is expected to happen.
"You can go and experiment on … the elephants at the Zoological Gardens. They're said to be highly intelligent, and they have this recommendation, that they don't come creeping about our bedrooms and under chairs, and so forth."
It is said that Appin was “teasing” the poor elephant with “German irregular verbs.” There is some humor at the end of the story in suggesting that he deserved his fate. No one is interested in the fact that the elephant killed Mr. Appin. He was praised at first for teaching the cat to talk, until people were not happy with the way the cat talked to them.
At first, people are curious but do not really believe that a cat can talk. Then Sir Wilfred confirms it, and then they are excited.
Appin had preached to absolutely incredulous hearers; Sir Wilfred's statement carried instant conviction. A Babel-like chorus of startled exclamation arose, amid which the scientist sat mutely enjoying the first fruit of his stupendous discovery.
The next thing you know, the cat is insolent and spreading rumors, and they are worried that talking will be contagious and talking about having it put down. They worry about the implications of a talking cat. All they want to do is forget it. When the cat dies, in a very catlike way during a cat fight, they are relieved and think that is the end of it.
Ironically, Mr. Appin, who tries to turn animals into people, dies when one proves that they are still animals. Either that, or it really was sick of German verbs! The notoriety he had as an animal trainer is completely gone. Not only is the fact that he was teaching the animal to talk not included, but the newspaper does not even know his name.
The victim's name was variously reported in the papers as Oppin and Eppelin, but his front name was faithfully rendered Cornelius.
Apparently, cats really are smarter than elephants, or this elephant did not care. Conversely, the humans do not seem to be the smartest ones in this story!