A: Our correspondent refers to the General Instruction of the Roman Missal, No. 160, which we quote in full along with the number which follows it:
"When receiving Holy Communion, the communicant bows his or her head before the Sacrament as a gesture of reverence and receives the Body of the Lord from the minister. The consecrated host may be received either on the tongue or in the hand, at the discretion of each communicant. When Holy Communion is received under both kinds, the sign of reverence is also made before receiving the Precious Blood."
[No. 161] "If Communion is given only under the species of bread, the priest raises the host slightly and shows it to each, saying, 'Corpus Christi' (The Body of Christ). The communicant replies, 'Amen,' and receives the Sacrament either on the tongue or, where this is allowed and if the communicant so chooses, in the hand. As soon as the communicant receives the host, he or she consumes it entirely."