It was a lenticel, a characteristic preparation from the elder-tree.    From Wordnik.com.  [The Country of the Blind, and Other Stories] Reference

Hill watched the clock hands until two minutes remained; then he opened the book of answers, and, with hot ears and an affectation of ease, gave his drawing of the lenticel its name.    From Wordnik.com.  [The Country of the Blind, and Other Stories] Reference