The Real Presence is attached, not to the chemical elements of bread and wine, still less to any ultimate atoms, molecules, electrons, or the like, but to the visible appearances of bread and wine. When these appearances disappear, the Real Presence is gone and the question is, what has happened to what is left. St Thomas here, and Sum. Theol. 3, q. 77, art. 5, seems to hold that what is left continues in the miraculous state of accidents functioning as substance to the end of time. But may we not plead against the saint his own words, that at that rate "by the frequent use of this mystery much of the corporeal nature originally created would have been reduced," not exactly to "nothing," but to a state bordering on nothingness? (Chap. LXIII.)
This solution is not commonly taken. See Pesch, S.J., Praelectiones Dogmaticae, vol. VI, pp. 311, 312.
Also that wary theologian, Cardinal Franzelin, writes: "When the accidents are so changed that naturally they would no longer point to the substance of bread and wine, but to some other, it becomes necessary for the Body and Blood of Christ no longer to remain under them. Were they to remain, it would be no longer the Sacrament instituted by Christ under the appearances of bread and wine. When this substance of the Body and Blood of Christ ceases to be under the changed accidents, those changed accidents connaturally require some substance to answer to them. As then upon the sufficient organisation of the foetus the creation and infusion of the soul follows according to a natural law laid down by God, so when the accidents are specifically changed and the Real Presence ceases, there follows the creation of a corresponding substance under those new accidents, and that, we may say, connaturally, according to a constant law laid down by God. This is equivalent to the restitution of the matter that was before consecration (De Eucharistia, pp. 240 sq. 293).
Of God and His Creatures: 4.66