Now he would have nothing.

He, Wilbur, would always remember Merle, even if he was no longer a twin, but Merle would surely forget him.

He had passed on.
Over by the little house he heard the bark of Frank, the dog.

Frank's voice was changing, and his bark was now a promising baritone.

His owner tried to whistle, but made poor work of this, so he called, "Here, Frank! Here, Frank!" reckless of betraying his own whereabouts.