So far, this novel has depicted Buck's complete transformation from the Southland civilized dog, living in the peaceful society of Judge Miller's estate in Chapter 1 into a dog that, through his strength and instinct and cunning, is quickly able to master the law of club and fang, and then in the middle chapter of the novel, we saw Buck becoming the master of the entire dogsled team. In contrast, in the last half of the novel, we have seen him almost destroyed by the incompetency and ineptness of three people of the Southland — Hal, Charles, and Mercedes. In the last chapter, we saw proof of how thoroughly Buck became a creature of deep loyalty and admiration to a man fully deserving this devotion. This final chapter, then, will present yet another view of Buck: his complete reversion to the primitive, or in the terms of this novel, his final surrender to the "call of the wild."
Returning to the narrative, we realize anew that John Thornton is now in possession of sixteen hundred dollars. Thus, he and Pete and Hans are able to pay off their debts, which they do, and then the three of them take off in search of a fabled lost gold mine, a mine which many have heard of, and many have searched for, but most have died searching for it. Yet the legend of the lost mine persists: "Dying men had sworn to it . . . clinching their testimony with nuggets that were unlike any known grade of gold in the Northland."
Even though the lost mine might be fictitious, or nonexistent, yet John Thornton and Buck are delighted to start out on a journey through "infinite wandering in strange places." The search for the lost gold mine is a traditional search which fills many adventure novels of Western literature; likewise, the search for the fabled Fountain of Youth, as well as the search for the Holy Grail, are other quests well known in Western literature. In each search, the participants have to undergo many trials and tribulations, but it is the quest itself that is, ultimately, as important as the discovery. In this particular quest, Thornton, Hans, and Pete move farther and farther away from civilization, and thus they are immersed deeper and deeper into nature's primordial conditions. Meanwhile, Buck devotedly follows his master in search of the lost gold mine, and, likewise, he is brought closer and closer to the primordial wilderness and its primitive existence.
As they travel, they almost always rely on their own ingenuity for food, and when food is scarce, they go without. There is no alternative. Months pass, and, as London says, they "twisted through the unchartered vastness where no men were." Once they do find the shambles of an old hunting lodge, and there they find remnants that indicate that other men have been here before. Then, in the spring, they find the place where the large, legendary gold nuggets are supposed to be. The men pan for gold, and, in London's words, "they heaped the treasure up. Buck spends many long hours close to the fire, and he remembers the "short-legged hairy man" who appeared in Chapter 3. The overwhelming memory which Buck has of this hairy man concerns Buck's being constantly frightened and, along with the memory of this ape-like figure, is the call of the wild, a call which Buck constantly hears in the forest. It causes strange and unknown feelings to rise within him. He is aware of some kind of primitive yearnings which he cannot identify. Employing the philosophy of Naturalism, London is apparently trying to juxtapose the dream of the "ape man" as being symbolic of the primitive element in all humankind; thus, this figure represents a kind of primitive ancestor calling to Buck, imploring him to respond and to return to the call of the wild.
After his dream of the hairy man, Buck becomes ever more entranced by the call of the wild. It becomes, finally, almost irresistible. Sometimes, according to London, Buck springs up from sleeping with a start, and from the forest, he hears a long-drawn howl, " . . . unlike any noise made by a husky dog." One time, he even follows the sound and comes upon an open place in a grove where he sees a lean timber wolf howling at the sky. Buck is much larger than this wolf, and so he chases the wolf into "one blind channel" after another, but he does so only to let the wolf know that he intends it no harm. Afterward, running through the woods with the wolf, Buck knows at last that he is answering "the call," running side-by-side with his "wood brother." It is almost as if he feels that he has done the same thing before — but in another world — "now only a dim memory."
In the midst of his re-introduction and re-immersion into the wilderness, however, Buck suddenly stops and remembers John Thornton, and he retraces his steps back to the camp where he finds John Thornton amused by Buck's actions. These scenes are, of course, showing Buck constantly fluctuating between being a part of civilization, as represented by Thornton, and concomitantly, showing the fascinating lure of the "call of the wild," represented by the baying of wild wolves.
Buck fluctuates; he spends a couple of days in camp with John Thornton, and then suddenly he becomes restless, and once again, he takes to wandering in the woods. Then, more and more, he stays away from the camp for days at a time. In the wilderness, he wanders about seeking signs of his "wild brother" — the wolf. He fishes for salmon, and, at one point, he even kills a large black bear because feelings have been aroused in him which are latent remnants of the primitive and the ferocious.
When he returns to the remnants of the bear two days later, he discovers a dozen wolverines at the spoil. The wolverines scatter at Buck's arrival, except for two bold ones, which he kills. After this, Buck's "blood longing becomes stronger . . . . He was a killer, a thing that preyed . . . surviving triumphantly in a hostile environment where only the strong survived." Because of Buck's Saint Bernard father, he had inherited a size and a weight far greater than that of the wolf, and from Buck's shepherd mother, he had inherited an intelligence and a cunning which became a "wolf cunning." Buck is almost transformed into a wild animal in the peak of condition — strong, powerful, cunning, vigorous, and alert. As John Thornton says, "Never was there such a dog."
Buck is now ready to complete his transformation from his previous civilized life to the ways of the wilderness. Whereas he was previously a devoted "friend" to John Thornton, he is now a wild creature who has learned to live by his own cunning and intelligence. Whereas earlier, he could kill any time he wanted to, he does not kill from "wantonness," cruelty, nor simply for the wild pleasure of it; he kills only when he needs food for his own preservation. Earlier, even when he was not hungry, he would practice those skills that he had already mastered — that is, he would trap various types of animals, simply for the thrill of trapping them, and then he would let them escape from him. Once, seeing a band of twenty moose, Buck chooses one exceptionally large buck, and "guided by that instinct which came from the old hunting days of the primordial world," Buck decides to stalk him, and while doing so, he notices that this particular animal has been wounded; it has a feathered arrow embedded just "forward of the flank," which causes the moose to be particularly savage. Each time that Buck lures the old moose from the rest of the herd, a younger bull moose comes to the aid of their old leader. At such moments, though, Buck merely lures him on and stalks him with the patience of the wild, a patience that is "dogged, tireless, persistent, as life itself." After a while, the younger bulls give up their protection of the old leader, realizing that it is more important to get the entire herd down to lower pasturelands. From that moment on, both night and day, Buck constantly stalks his prey, in a relentless manner, never permitting it to relax. At the end of the fourth day, Buck finally pulls the great moose down, and after enjoying the kill, he feels refreshed and renewed and decides to find John Thornton's camp.
London's purpose in having Buck kill the wolverines and his stalking and killing the moose is to let the reader know that Buck has now totally mastered the ways of the wilderness; from now on, Buck will be able to survive in the wild without any help from human beings.
Returning to camp, Buck discovers a fresh trail which creates suspicion in him. Thus, he approaches the camp with a great deal of caution; there, he finds Nig, one of Thornton's dogs, lying dead from an arrow's poisoning. Farther on, Buck finds another of Thornton's dogs dead. Creeping cautiously on his belly, Buck finds the camp in shambles, and for the last time in his life he allows passion to usurp cunning and reason" — all because of his great love for John Thornton. Suddenly, he sees the reason for the bloody chaos: the Yeehats, a band of ferocious Indians. Without caution, he begins to attack one Indian after another, tearing out their throats. His newly untamed ferocity continues until all of the Yeehats are seized with panic and flee in terror, thinking that they have seen the Great Evil Spirit.
Buck pursues the Indians briefly, then returns to the camp, where he finds Pete dead in his blankets and then he discovers Thornton's body half-submerged in water. As Buck surveys the carnage of the camp, he realizes a strange pride — greater than any he had yet experienced: "he had killed man, the noblest game of all, and he had killed in the face of the law of club and fang." Thus, the story has come full circle: in the first chapter, when the man in the red sweater taught Buck that a man with a club would always be the master of an animal, Buck now has proven himself to be superior to men — even men with arrows and spears and clubs.
When Buck attacked, the men fled in terror. And now that John Thornton is dead, Buck has no more ties with civilization. So, as Buck stands in the center of the camp site, a great open space, he realizes that all of his ties to civilization are broken, and he hears again "the many-noted call of the wild," which sounds more luring and compelling than ever before.
When a pack of wolves moves close to the camp, one of the large wolves attempts to attack Buck, and the wolf is immediately killed. Three others attack and withdraw, streaming with blood from slashed shoulders and throats. The entire pack, then, pins Buck down so that he cannot escape, and he is forced to fight the entire pack alone. At this point, one of the wolves advances cautiously, and in a friendly manner, he touches his nose to Buck's. It is the wolf that Buck had run with earlier. Buck has now become a member of the wolf pack, and, as London says, he "ran with them side by side . . . yelping as he ran."
London closes the novel by telling us that Buck becomes mythic in proportion, and a legend spreads from generation to generation. The rumor becomes so widespread, in fact, that the valley where Buck first encountered the Yeehats becomes known as the home of the Great Evil Spirit, and no one dares to approach that valley. Furthermore, over the years, Buck creates a new breed of animal — marked with light patches of hair, which is, of course, inherited from Buck. Buck has truly answered the call of the wild; the civilized animal has become the leader of a pack of wolves. The call of the wild has been heard, and it has been answered magnificently.