Note 876 — BOOK XIX. THE NATURE AND CULTIVATION OF FLAX, AND AN ACCOUNT OF VARIOUS GARDEN PLANTS.
John Bostock translation
This callous secretion of the earth, or corticle, is, as Fée says, a sort of hymenium, formed of vesicles, which, as they develope themselves, are found to contain diminutive truffles. Pliny is wrong in saying that the truffle forms neither cleft nor protuberance, as the exact contrary is the fact.