Hegesippus:
Hegi[e]sippus of the Five Memoranda?

Did Eusebius quote you accurately? I’ve always wondered.
It’s just probably just that it’s hard to spell “paedocommunion,” or that the liturgical historians who might post are away for a while, or that we’re all thinking how fortunate you are to be taking a theology class and want to encourage you to dig into the question with the zeal of a student.
If you’re studying at Catholic University, where I did some time, and they’re done with the renovations and reshelving, the library’s probably reasonably functional. I thought Mullen had quite an adequate theological-historical-liturgical collection.
You also have the fortune to be able to use technology and gather references through the internet so that you can then look them up in books, or even, depending on institutional policy at CU, use accurate e texts where they exist in some scholarly citation.
Primary sources are always best though. You’ve mentioned Trent and Lateran IV. Just read them now.
There are some reasonably accurate e-texts on the web, and most libraries have collections of the Ecumenical Councils (such as Tanner) easily available. Trent’s all over the web. Find Lateran IV at
fordham.edu/halsall/basis/lateran4.html .
The old internet standby of the Catholic Encyclopedia, while outdated as to subsequent developments in law, liturgy and ecclesiology, still presents accurate historical references.
newadvent.org/cathen/04170b.htm would offer you the references you to start with other sources.
Make friends with The Early Church Fathers at the Christian Classics Ethereal Library. It’s a wonderful place to start if you don’t have access to a comprehensive theological library. For example, Cyprian, de Lapsi, can be seen at
ccel.org/fathers2/ANF-05/anf05-113.htm
Still you might want to consider the important patristic sources apart from those mentioned in that New Advent “monumentum”: the Apostolic Constitutions, and Augustine (against the Pelagians [174,7]).
Quam Singulari (Decree Of The Sacred Congregation Of The Discipline Of The Sacraments On First Communion, 8 August 1910) references the concern that infants would “eject the Consecrated Host,” so that the practice of administering only the Precious Blood to them became normative. As you know, discussion of that then would turn to the other issue of why that practice ceased of administering communion in the form of wine. (I vaguely recall that apart from theological questions and the general decline in receiving communion at all, this also had something to do with colder climates in Europe, especially England, and failures in the grape crops.)
But in considering the First Council of Toledo (can. 14), that particular problem of reverential consumption must have been a concern from early times. As well, Dionysius’ Ecclesiastical Hierarchy references that there was a early controversy about this on the basis that infants could not understand the sacrament (or Baptism for that matter).
The canonical reference in the present Latin code would be canon 913 , and from the former code, see canon 854 §2. In regard to Eastern practice, see Orientalum Ecclesiarum, 12 and canon 710 of the code of canons of the eastern churches.
Generally I think that Fourth Lateran Council, the regional Council of Bordeaux and the Council of Trent, argued that since baptism protected the child from accountability, there was just no reason to administer communion to infants.
But I’d encourage you to discuss that with one of those professors in Religious Studies at CUA. They have more letters after their names than the Cambodian alphabet.
Good luck and God’s speed!
