One day, Dave, one of the sled dogs, becomes irritable and constantly cries out in intense pain. The drivers can locate no broken bones or visible wounds, but they know that something is wrong, probably internally. The Scotch half-breed, therefore, decides to remove Dave from the team; yet Dave, even in his pain, is resentful. London explains that "the pride of trace and trail was his, and, sick unto death, he could not bear that another dog should do his work." So he runs alongside the sled, which causes him excruciating pain because he deeply desires to be a member of the team. The driver is concerned by Dave's actions, and his comrades "talked of how a dog could break its heart through being denied the work that killed it." The driver decides to harness Dave again, even though he knows that it will surely kill him. The next morning, Dave is too weak to travel, but through an incredible act of physical stamina, Dave bravely stands in line to be harnessed. He constantly trips and falls, and he stumbles, unable to pull along with his teammates, and at last, the driver is forced to remove Dave from the team. Retracing his steps to the camp, the Scotch half-breed takes Dave back with him, and as Buck listens from a distance, there is a crack of a revolver, ending Dave's life on the trail.
In general, this chapter functions as something very much like a transitional chapter. In the first three chapters, we saw how Buck adjusted to the primitive wilderness and to the primeval North. After his winning his mastership in this chapter, we see that Buck now performs the tests of his masters with perfect precision, making himself a lead dog superior even to all the other dogs. Thus, Buck proves to be a perfect creature. This transitional chapter contrasts with the first three chapters, then, and the next three chapters will show Buck becoming increasingly alien to all traces of civilization and preparing himself to accept and adapt to "the call of the wild."
