Assertion: vacuole | /r/CapableOf | appear at interval
Facets:
Source sentences:
text: The protoplasm is more or less extensively excavated by fluid spaces, vacuoles; one clearer circular space or vacuole, which is invariably present, appears at intervals, enlarges gradually, and then vanishes abruptly, to reappear after a brief interval; this is called the contractile vacuole (c.v.).