Whitey looked at Injun in wonder and alarm.

Injun looked at Whitey with no expression of any kind.
"Mebbe they've killed Slim!" cried Whitey.
"Mebbe," Injun agreed.
Sitting Bull had silently followed the boys, and while they were investigating with their eyes, he was doing the same with his nose.

His search had led him to a bunk, and with his fore paws on its edge, he was gazing into it, his head on one side and a very puzzled expression on his face.

Bull rarely barked, except to express great joy, and he never was afraid.

His nose had told him what was in that bunk; the curious movements of the object were what puzzled him.