The Indian Figurines
Literally, a figurine is a small representation of a human or animal figure. In the novel, the Indian figurines provide a convenient way for the murderer to demonstrate that the guests are being killed one by one. Thus, they serve as a psychological device for enhancing the guests' fear. However, the figurines also serve as a plaything for the murderer. Like game pieces, they demonstrate that each guest is a pawn of the murderer. Their diminutive nature also suggests the insignificance of each guest.
The Nursery Rhyme
The "Ten Little Indian Boys" nursery rhyme foreshadows the guests' manner of death. However, the playful rhymes of the poem also serve as a stark contrast to the gruesome murders. As a symbol, the rhyme further illustrates the child-like or game-like approach to death Wargrave takes. In addition, the rigid structure of the rhyme reflects the murderer's carefully orchestrated plan.
Poison is both a literal and a figurative device in the novel. Several of the guests are killed by poison: Marston and Brent die from cyanide poisoning, while Mrs. Rogers dies from an overdose of a sedative. Ironically, the guests initially believe that Marston poisoned himself. And in a sense he did, for his reckless actions ultimately brought on his death. As such, the novel suggests that it is possible to "poison" one's life through one's actions. It is significant that Marston and Brent are killed by cyanide poisoning, for it results in asphyxiation. Metaphorically, several of the guests are asphyxiated by their own sense of guilt and conscience. Wargrave's obsessions with death and justice can also be said to have poisoned his mind.
Indian Island symbolizes isolation in several forms: it segregates the guests physically, psychologically, and socially. The island is a fitting location, since each guest's act of murder has isolated him or her in some way. Of course, once the guests set foot on the island, of their own volition, there can be no escape.