Note 7 — Chapter IX

I found here a species of cactus, described by Professor Henslow under the name of Opuntia Darwinii (Magazine of Zoology and Botany, vol. i., p. 466), which was remarkable by the irritability manifested by the stamens, when I inserted in the flower either a piece of stick, or the end of my finger. The segments of the periant also closed on the pistil, but more slowly than the stamens.