caused the team to run out of food, they trade for some “frozen horse-hide” that “was more like strips of galvanized iron, and when a dog wrestled it into his stomach it thawed into thin and innutritious leathery strings and into a mass of short hair, irritating and indigestible.”

Chapter 5 of The Call of the Wild is where Buck and the sled dog team meet their new owners, Hal, Charles, and Mercedes.  Those three would be termed "city slickers."  They do not know anything about nature, the wild, survival, sled dogs, etc.  This is evidenced by how much stuff they attempt to load onto the sled.  

Hal, Charles, and Mercedes could be representative of consumerism and materialism.  The stuff they own makes them feel important or rich, and the thought of not having it does not cross their minds.  When it becomes evident that the sled is indeed too heavy, the decision is made to get rid of some of the weight. Unfortunately, Mercedes keeps many of her fashion items and throws out survival supplies like food and water.  Again the emphasis is on their attitude toward material possessions.  London is emphasizing the difference between their attitudes and that of the attitude necessary in the wild.  The value of an item in the wild is in its immediate usefulness, not its symbolic representation of wealth.  Ultimately, Mercedes's death occurs because of her materialistic attitude. 

A symbol is normally a tangible, concrete item that represents something more abstract. For instance, in Call of the Wild, the man in the red shirt is wearing a symbol -- the red shirt. The color red can be used to symbolize a number of different emotions or signals: danger, rage, intense hatred, or even the idea of stopping, such as when we see a red light.

The red shirt is symbolic of the lesson learned by Buck at the hand of the man in the red shirt -- he is the man who beats Buck and other dogs severely using a club, and Buck learns "man's law" through the violence of the man in the red shirt, who is never given another name. Hence, the red shirt is symbolic of the above mentioned emotions -- rage, hatred, and intense distrust.

The club itself could also be considered symbolic, as it represents man's abuse and torture of animals in the Yukon. It isn't until Buck meets John Thornton that he is treated with the civility and respect he deserves. All his other masters, including Perrault and the others, may have treated him somewhat kindly, but not with the love and compassion that Thornton exhibits. 

A symbol is something that stands for something other than itself.  One of the symbols in the story is the club.  For Buck, the club is a symbol of man’s power over animals.  Buck learns the Law of Club and Fang from the man in the red sweater, a dog breaker.

When Buck is sent to Alaska to be on a sled dog team, he is miserable.

All was confusion and action, and every moment life and limb were in peril. There was imperative need to be constantly alert; for these dogs and men were not town dogs and men. They were savages, all of them, who knew no law but the law of club and fang. (Ch. 2)

Buck lived by the Law of Club and Fang after this. It meant that he would listen to whoever was stronger than him, whether dog or human.  It was all about who was strong and who was weak.  Thus the club is more than a club.  It is a symbol of strength.

Another important symbol in the book is the Call of the Wild itself.  The call is not a literal call, although it can refer to a wolf’s howl.  The actual Call of the Wild is the draw to return to nature.  Buck was a domesticated dog, but the longer he was in the wild the wilder he got.

Whereupon the old wolf sat down, pointed nose at the moon, and broke out the long wolf howl. The others sat down and howled. And now the call came to Buck in unmistakable accents. He, too, sat down and howled. (Ch. 7)

After Buck is rescued from the people, and then loses John Thornton, he returns to the wild.  Buck answers the call because he has learned the ways of the wild, and it is preferable to being answerable to humans.  He is strong enough to become like a wolf.

I like the symbol of Mercedes and her possessions.  She, and all of her stuff, represent materialism.  She believes that having all of her stuff makes her important and powerful.  She is adamant that it get loaded onto the sleds even though it is too heavy for the dogs to pull. Mercedes can't recognize that out in the wild material possessions are valued very differently than in cultured society.  To Mercedes, her possessions are meant to reflect her value and importance.  In the wild, the worth of a possession is based on its immediate value for survival.  Mercedes doesn't get it.  And it kills her. 

I think a second main symbol is the lone wolf.  I believe that the lone wolf represents Buck's desire to be free of man and society.  Buck wants to be like the wolf and make his own decisions and hunt and kill.  If it weren't for John Thornton, Buck probably would have left a lot earlier to follow the lone wolf.  But once the Yeehats kill Thornton, any ties Buck felt toward man are severed.  Buck goes wild, literally.  He kills a bunch of the Indians, then takes on the wolf pack leader, and finally fully embraces his call to the wild. 

Jack London's fiction typically establishes a dichotomy between civilized and non-civilized worlds. The subtext is generally the question: is one realm "better" than or preferable to the other? In The Call of theWild, Buck is taken from his home in California and thrust into a new, harsh environment which is a kind of hell on earth for him. Ironically, however, it leads him to fulfill his inner nature that could never have occurred if he had continued his peaceful life as a domesticated dog.

The "Northland," the harsh, forbidding Yukon territory into which Buck is taken and where he is to live out the rest of his life, is a symbol of the wild, uncivilized external world as well as the primitive inner world from which we—both humans and domesticated animals—have presumably escaped.

But it is also a symbol of liberation. Buck is transformed into a new being when he is forced to become a working dog who pulls a sled. When he's rescued by John Thornton, he bonds with him and becomes devoted to a human who has an intensity and a completeness: the kind of person who he would not have found had he remained in the Southland, in California.

Finally, when he does in fact return to "the wild," he is a leader, paradoxically reverting to his ancestral roots but also becoming a "greater" being (both physically and, in some sense, spiritually) as well as the head of a wolf pack. The trajectory of Buck's story is a symbol of this process of liberation.

London's point may not be that the wild world is "superior," but that—just as we humans must progress beyond our initial state of childlike innocence and become adults—Buck, through the suffering he endures (including the loss of John Thornton), has progressed beyond the cocoon of innocence and become a more complete being.

The story of The Call of the Wild is therefore itself a symbol of maturation and of the expulsion from the Garden of Eden into the "real" world—a place where both pain and triumph are possible, as they would not have been in the ignorance of paradise.