This, and the drawing to the right, come from a group of over 100 records of citrus fruit in the ‘Paper Museum’. Cassiano had them engraved to illustrate a treatise on the cultivation of citrus fruit, written by his friend Giovanni Battista Ferrari, who enthused at length about the size of the pummelo, one of the largest citrus fruits. However, as the cross-section below shows, much of the fruit’s bulk is made up of a thick pith.