A moment of foreshadowing is found in Ma's conversation with Al when she responds to his concern about bringing Casy along with them to California, "You'll be glad a that preacher 'fore we're through." Their decision to include the preacher into their family will prove fortuitous immediately, when he is called upon to help with Granpa's funeral, and more importantly later in the story, when he gives himself up to a sheriff so that Tom is not jailed.
Granpa's death and the "adoption" of the Wilsons in this chapter reveals a change in the family structure that supports the theme of social unity: The concept of the individual family is being replaced by a larger concept of a world family. Granpa's death is the first loss the family endures, and it is instrumental in drawing the family together as a unit. As a group, the Joads — and now also the Wilsons — must decide what to do with their corporate family body, and in deciding, create their own laws based on what Casy refers to as the "have-to's." This group government dynamic, already witnessed in the family conference in Chapter 10, will be seen in greater scope in the government camp in California. The "adopting" of the Wilsons into the family furthers the concept that communal unity is necessary for survival. Several symbolic gestures unite the two families: Granpa dies in the Wilson's tent, Sairy Wilson's quilt is used to wrap his body, and a page torn from the Wilson's family Bible is buried with him. In deciding to travel together, the two families instinctively fulfill Casy's speculation that it is only by working together that they can survive the trek to California. As Ma puts it, "Each'll help each, an' we'll all git to California."
