Read this sentence from “The Gift of the Magi” and answer the question. Jim stopped inside the door, as immovable as a setter at the scent of...

Jim stops frozen in his tracks. His reaction is probably that he thinks he may have entered the wrong apartment by mistake. He doesn't even recognize his wife at first. He thinks he is looking at a stranger, and he doesn't understand what this strange woman is doing in his apartment and what has become of Della. Della was expecting a strong reaction from her husband when he saw her without her long hair--but she didn't know what kind of reaction to expect. Jim's reaction is completely outside the bounds of anything she might have expected because she can't really see herself as another person might see her. She has already become familiar with her new appearance, since she has spent hours looking at herself in the mirror and trying to do something with her short remaining hair. 

Jim's reaction shows the enormous change that has taken place in Della's appearance. He is, of course, used to coming home every night and seeing the same young woman with the same long hair. This is actually the first time that the reader gets a full realization of how different Della must look. Jim's reaction would not be one of surprise, shock, astonishment, dismay, or any such emotions. It would be one of complete disorientation. Where am I? How did I get in here? Who is this woman? What is she thinking? Is she going to scream for help? This is because he expected to see one familiar woman and sees a complete stranger. The transformation was so radical because women wore their hair so long in those days. 

So now Della's beautiful hair fell about her, rippling and shining like a cascade of brown waters. It reached below her knee and made itself almost a garment for her.

Then his own wife gradually comes into focus in his brain with her new look. O. Henry has done a masterful job of describing Jim's reaction. The reader, like Della, didn't know what to expect of Jim when he saw her. O. Henry hit upon exactly the right reaction of disorientation. Jim was not expecting anything new. Jim's reaction is funny and was intended to be funny.