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.