What is the effect on Roger in his view of Ralph and Piggy as "a shock of hair and a bag of fat" respectively?William Golding's Lord of the Flies

As the boys remain on the island, their descent into
savagery gains momentum.  The sadistic Roger, whose arm "was conditioned by a
civilization that knew nothing of him and was in ruins," no longer throws stones that
miss Henry as he has done in Chapter Four of Lord of the Flies. 
Now, he can give free reign to his brutal nature.  His characterization of Ralph and
Piggy as "a shock of hair and a bag of fat" suggests his total rejection of the
leadership of Ralph and the rationality of Piggy and of Piggy's similarity to adults as
representatives of society and civilization.

Once he has
dehumanized Piggy and Ralph, Roger, who is the most brutal of all the boys, has no
qualms about satiating his morbid enjoyment of being
cruel:

High
overhead, Roger, with a sense of delirious abandonment, leaned all his weight on the
lever.

Continuing in his
sadism, Roger hurls a spear at Ralph below.  When he climbs down from the mountain,
Roger "

edged
past the chief, only just avoiding pushing him with his shoulder.  The yelling ceased
and Samneric lay looking up in quiet terror.  Roger advanced upon them as one wielding a
nameless authority.

Roger, of
the cruelest nature from the beginning of the novel, now has given full rein to his
sadism, indicating the state in which the hunters now are.  The "nameless authority"
with which he advances is anarchy.