What does "sizar" mean?

Sizar: One of a body of students in the universities of Cambridge (Eng.) and Dublin, who, having passed a certain examination, are exempted from paying college fees and charges. A sizar corresponded to a servitor at Oxford. The sizar paid nothing for food and tuition, and very little for lodging. Macaulay. Note: They formerly waited on the table at meals; but this is done away with. They were probably so called from being thus employed in distributing the size, or provisions. See 4th Size, 2.