Describe Buck's encounter with his wild brother?

The wolf motions for Buck to come with him, and Buck is wildly happy as they run. He now understands what the call meant, running wild and free with his brothers. Suddenly, Buck remembers John Thornton. He turns back, and for an hour the wolf runs with him, confused, but finally Buck must go alone. When he enters camp he overwhelms John Thornton, so happy is he to see him. For two days he does not leave the camp or let John Thornton out of his sight. Then he once again becomes restless. Buck sleeps away from the camp, wandering the forest and searching for his wolf brother for days a time.