What do 'sprang for' and closed on the hand' here mean?
The hoarse shriek of a locomotive whistling a crossing told him where he was. He had travelled too often with the Judge not to know the sensation of riding in a baggage car. He opened his eyes, and into them came the unbridled anger of a kidnapped king. The man sprang for his throat, but Buck was too quick for him. His jaws closed on the hand, nor did they relax till his senses were choked out of him once more.