spore vs vacuole

spore

noun
  • A reproductive particle, usually a single cell, released by a fungus, alga, or plant that may germinate into another. 

  • A thick resistant particle produced by a bacterium or protist to survive in harsh or unfavorable conditions. 

verb
  • To produce spores. 

vacuole

noun
  • A large membrane-bound vesicle in a cell's cytoplasm. 

  • A small empty or air-filled space or vacuity. 

How often have the words spore and vacuole occurred in a corpus of books? (source: Google Ngram Viewer )