This is an excerpt from Alte Kochrezepte aus dem bayrischen
(Germany, ~1500 - V. Bach, trans.)
The original source can be found at
Stefan's Florilegium
Jellied fish. Take the resin of cherry trees, dry it and grind it and put that into the jelly while it is hot. It will gel quickly.
Recipes with similar titles:
62 How one should make jellied fish (Das Kuchbuch der Sabina Welserin)
Jellied fish (Alte Kochrezepte aus dem bayrischen)