in Thoreau’s Journal:
Heard in the night a snapping sound, and the fall of some small body on the floor from time to time. In the morning I found it was produced by the witch-hazel nuts on my desk springing open and casting their seeds quite across my chamber, hard and stony as these nuts were.
For several days they are shooting black seeds about my chamber…I suspect it is not when the witch-hazel nut first gapes open that the seeds fly out. For I see many, if not most of them, open first with the seeds in them; but when I release a seed, it being still held by its base, it flies, as I have said. I think that its slippery base is compressed by the unyielding shell which at length expels it just as I can make one fly by pressing it and letting it slip from between my thumb and finger. It appears to fit close to the shell at its base, even after the shell gapes.