Do chicks in eggs excrete? I want to know if, as a baby chick grows inside the egg, does it excrete waste? If it does excrete waste, does the waste just sit inside the egg with the chick, until the chick cracks open the egg and gets out?

Yes they excrete uric acid which is stored in the allantois of the embryo; which acts as a reservoir of nitrogenous waste.

Uric acid is not very soluble in water, so it stays as a small solid mass.