What is the meaning of throwing of the stones at the end of "The Lottery"?

The ending of Jackson's story is the realization of the
town's tradition or practice of throwing stones and pelting one "chosen" individual in
the village.  In the story, the "chosen one" is Tessie Hutchinson.  The meaning of the
villagers throwing stones is both literal and symbolic.  On the literal end, the
villagers literally circle around one individual in the village and pelt that person
with stones until they are dead.  The opening of the story reflects this as children are
running around, building and guarding their piles of stones.  A seemingly harmless
action is brought to greater significance when Mrs. Delacroix, Tessie's close friend
throughout the story, runs over to find a stone so big that she needs two hands to carry
it.  The ending of "and they were upon her" reflects how the town draws the one person
who will be pelted with stones.  The meaning of throwing stones is an act of targeting
and exclusion, whereby one person is selected to be victimized as "the other."  In a
more symbolic meaning, the act of throwing stones at the end of the story is an
inversion of the Christian notion of "let he who is without sin cast the first stone." 
In Jackson's short story, all of the "sinners" are freely casting stones at one who is
relatively blameless in the process.  The symbolic meaning of being able to throw stones
also reflects a very savage and primal way of resolving conflicts, symbolic of how the
practice of silencing voices is something that has been around for as long as time
itself.  In this, the idea of casting stones is something that reflects the sad, but
time honored practice of targeting individuals as the recipients of social scorn and
rejection.