How we cite our quotes:
[H]is parents – who had never rented out rooms before and therefore behaved toward the roomers with excessive politeness – did not even dare to sit down on their own chairs. (3.12)
Gregor's transformation also results in an upheaval in his family's social status. For the first time, they have to take in boarders to make ends meet. Unsure of how to treat their boarders, they cannot act naturally in their own home.
"Mr. Samsa!" the middle roomer called to Gregor's father and without wasting another word pointed his index finger at Gregor, who was slowly moving forward […] His father seemed once again to be gripped by his perverse obstinacy to such a degree that he completely forgot any respect still due to his tenants. (3.14)
After Part 1, there is precious little dialogue in the story, and, when there is dialogue, you get moments like these. (It seems that Gregor isn't the only person in the family who has lost the power of speech.) The middle boarder's calling out Mr. Samsa bears a striking parallel to the scene where Grete calls out Gregor's name (see Quote #4 above). We think of our names as being an integral part of who we are, but in both this quote and in Quote #4 we see names being used not so much to identify a character, but to point out an instance where the character doesn't seem to act like himself. In Quote #4, Grete calls out Gregor's name when Gregor is acting like a gross bug; in this quote, the middle roomer calls out Mr. Samsa when there's a breach in the way the household's run.
The couple Mr. and Mrs. Samsa sat up in their marriage bed and had a struggle overcoming their shock at the cleaning woman before they could finally grasp her message. (3.31)
At this late, late point in the story, it sounds almost too formal to call Gregor's parents "Mr. and Mrs. Samsa." Because we get most of the story from Gregor's perspective, his parents are usually referred to as "his father" and "his mother." By calling them by their names here, the story emphasizes that Gregor has indeed died – we're no longer going to get anything from Gregor's perspective.