The cub develops rapidly, but then there comes a famine upon the land, and the she-wolf runs herself thin in search of meat. The famine becomes so terrible, in fact, that the she-wolf becomes desperate — so desperate, in fact, that she is finally forced to raid the nest of the lynx, knowing full well that the lynx is a vicious animal and is fully capable of killing her. Nevertheless, she raids the lynx's nest and brings back the four lynx kittens, and she and her gray cub devour them. The mother lynx, not unsurprisingly, comes to the she-wolfs lair for revenge, and the she-wolf is no match for the powerful lynx until the young gray cub rushes forward and sinks his teeth into the hind legs of the lynx. This so hampers the lynx that, together, the mother and her cub are able to kill the fierce lynx. However, during the battle, the cub's shoulder is ripped to the bone, and the she-wolf is wounded almost to the point of death. From this encounter, the gray cub learns another lesson: "the aim of life was meat. Life itself was meat. Life lived on life. There were the eaters and the eaten. The law was EAT OR BE EATEN."
Basically, this part of the novel focuses on the lessons which the gray cub learns — that is, eat or be eaten, or, in simple ecological terms, animals kill other animals for food. Also in this chapter, London gives us a vivid picture of many aspects of life in the wilderness, and not only does he show us the savagery with which one animal kills another animal for food, but he also shows us how a mother wolf, or a mother ptarmigan, a mother weasel, or a mother lynx, will endanger themselves in order to protect their offspring. Part of the law of the wilderness, therefore, is that of instinct — which the gray cub quickly learns and develops.
By extension, London is using his own philosophy of Naturalism, believing that man is a victim of a hostile universe. Therefore, in this novel, London shows us that in the wilderness, as well as in the life of civilized man, all is "blindness and confusion. . . . violence and disorder, the chaos of gluttony and slaughter, ruled over by chance [which is] merciless, planless, endless."
