Question: During the Mass, the priest “drops a particle of the Sacred Host into the chalice”. What does this signify?
Answer(s): In the Early Church, the Pope (and other bishops) would send pieces of consecrated hosts to other bishops and priests, who would drop them into the chalice as a sign of unity with the Pope and other bishops.
Another meaning is that a particle of a previously consecrated host is dropped into the chalice signifying the continuation of the One Sacrifice.
This act also represents the unity of the body and blood of Christ in the consecrated host and wine.