Handbook of Liturgical Practice of the Russian Church Abroad
When removing particles from the fourth and fifth prosphora of the Proskomedia (i.e. for the living and the departed), as well as from all offering prosfora sent into the Holy Altar by the faithful, accompanied by lists of those to be commemorated, the Priest is to remove a particle from the prosphora for each name being commemorated. That is to say, he is not haphazardly removing particles at random from the loaves whilst reading names; each name is associated with a particle deliberately removed from the prosphora and, in due course, placed upon the diskos in the appropriate place.
In recent generations, a habit of merely ‘twirling’ the spear against the prosphora, so that fine crumbs fall constantly, at random, whilst the Priest reads names, has become widespread. This represents a carelessness that should be guarded against; Priests who may have fallen into this habit should work diligently to overcome it.
Examples of particles properly removed from prosphora for commemorations.
It may well be impossible, if a sudden surfeit of commemorations is presented to the Priest late into the period before the Liturgy, or during it, for him to extract particles for each name thus presented in the full manner. In such a case, he may choose by necessity to extract only a smaller number of particles from a prosphora whilst reading all the names; but this is an act of economia out of necessity, and should be avoided when possible. This of course requires the Priest to begin the Proskomedia early enough that he can piously make all the regular commemorations of parish’s lists and commemoration books in an unhurried way; but it also requires the education of the parishioners, so that they come early enough before the Liturgy (i.e. during the Hours) and send their lists into the Altar, not at the last minute, but in good time so as to enable the Priest to make their commemorations properly.
See a separate entry in this Handbook, on Altar Servers assisting the Priest in reading commemoration names, in larger parishes.