Read this excerpt from the call of the wild.

for two days and nights buck never left camp, never let thornton out of his sight. he followed him about at his work, watched him while he ate, saw him into his blankets at night and out of them in the morning. but after two days the call in the forest began to sound more imperiously than ever. buck's restlessness came back on him, and he was haunted by recollections of the wild brother, and of the smiling land beyond the divide and the run side by side through the wide forest stretches. once again he took to wandering in the woods, but the wild brother came no more; and though he listened through long vigils, the mournful howl was never raised.

how has buck changed?

he has become more anxious about the call from the wild.
he has become less haunted by his dreams.
he has become more loyal to all mankind.
he has become less aware of his past life as an obedient pet.