What is the reason for the narrator telling about his brother’s experiences?

The narrative suddenly switches to the perspective of the narrator’s younger brother, a medical student. The brother had read in the papers that Martians had landed near Woking and killed a few people, but the paper assures its readers that the Martians will be unable to function in the dense atmosphere of Earth. Still, the narrator's brother makes up his mind to visit the narrator the next day. The brother offers a medical perspective over the invasion and people that are affected.