Definition of "nematocyst"

Often one sees, on surface view, a distinctly rounded vacuole, occupying a position in the cell occupied in others by a large nematocyst.

1885, R. J. Harvey Gibson, “Observations on the nematocysts of Hydra fusca”, in Proceedings of the Literary and Philosophical Society of Liverpool‎, volume 39, page 30

The young nematocyst decreases in size and becomes coarsely granular, the granules arranging themselves in a spiral line close under the external membrane.

1902, Arthur Willey, Zoological Results Based on Material from New Britain, New Guinea, Loyalty Islands and Elsewhere‎, page 379

Nematocyst discharge is another example of the Rubicon principle – it either fires or it does not.

2014, Anthony K. Campbell, Intracellular Calcium‎, page 350