Explain how Buck went from California to the North

Buck lives in the home of Judge Miller in Santa Clara Valley. The house is large and spacious, and the grounds are beautifully laid out with orchards and gardens. Unknown to Buck, he is in danger. Manuel, a gardener's helper, has amassed a large gambling debt. His salary can barely support his large family, and there is little left to help him. One night, when the Judge and his sons are gone Manuel takes the unsuspecting Buck on a walk. They arrive at a flag station where a man is waiting for them. Money changes hands, and Manuel ties a stout rope around Buck's neck. When the stranger tries to take the rope, Buck growls, and the rope tightens, cutting off his breath. He flies violently at the man, only to be choked repeatedly. Despite his fury, Buck is thrown into the baggage car of the train.