In the depiction of Buck above, as Buck lived in the icy north struggling with the arduous sled work  
and environment, the gradual changes of Buck was clearly and obviously undertaking, although he himself was unconscious of all of this. The dim and distant image of the sunland means his gradual detachment from civilization; the sounds and sights of another world is the very free and primitive life in the wild with brutality and challenges; the potent memories of his heredity and life in the north make him exited, which symbolizes his more adaptability to the wildness, or in other words, the call of the wild is much more closer to Buck.  

When he gradually realized the recovery of his instinct, Buck came across his new master, John Thornton. However, he could not stop the steps heading forward to the wild. After the final revenge for his master, Buck dismissed all from the human civilization and became a master of his own, a master of nature. He ran straightly towards the call of the wild.  
4 Human Society Reflected by the Wild
 is not only a story of Buck’s adventurous transformation in the wild, but also a story in which the dog’s life reflects truths about the human condition and society at that time. In this sense, the novel has some resemblance to the literary form, beast fable, which gives human characteristics to animals in order to illustrate and satire human society and human nature.

4.1 An Allegory of the Man
In the dog group, the dogs are all given different characteristics and are described with adjectives usually given to human beings. Curly is good natured. The head dog Spitz is tyrannical and cunning with ticks in mind. Dove is old and wants to be left alone, having no interest but eating and sleeping.  The twin brother Billee and Joe are as different as day and night. Billee has excessive good nature while Joe is sour and introspective, testy and mean-tempered. An old husky called Solleks gives others continuing warnings of prowess that commands respect. He asks nothing, gives nothing and expects nothing in life. Buck, on the other hand, is a more complex humanized animal with different aspects of characteristics. Throughout the story, in human perspective, Buck observes everything happened and draws his own conclusion and lessons. He always seems to understand human languages. John Thornton once said to Buck, “God, you can all but speak!”(Wang, 2011, 67). In the novel, Buck was given many characteristics and disposition of man such as bravery, honest, self-respect, intelligent, reflective, imaginative, having dreams and illusions, nostalgic, dauntless and so on. 自然主义在《野性的呼唤》中的体现(8):http://www.youerw.com/yingyu/lunwen_132.html