No, they're part of the original song and go exactly where they are placed in the DT. See Jim Dixon's post above from 8/19/10, and this time click on the link in it. This takes you to the 1930 recording by the Carson Robison Trio. Frank Luther is the singer, doing a dead-on Vernon Dalhart impression.

The verse consists of three strains: "Stop a while and listen ... " followed by "I returned to look ..." which ends on a II7-V7 "Where we carved our hearts long ago." Then "[V7, held from the end of the previous strain]But the old pine tree it was gone/Still my [II7]love for her lingers [V7] on," and into the chorus, which also has two strains. Makes perfect sense if you listen to the record.

At one time I owned both Conqueror 7732, with the Robison/Luther recordings of this song and "She Was Bred in Old KY", and the 1930 sheet music, the latter picked somewhat idly from a box of old music which I've kicked myself ever since for not negotiating a "how much for the whole box" price. Most of it was 1920/30 pop, which at the time did not particularly interest me.