In taxonomic terms, life on Earth was no longer limited to the animal and plant kingdoms, but new kingdoms-fungi, bacteria, and protoctista (protozoa, algae etc.) -had to be recognized, to bring the total number to five. Each of the kingdoms of micro-organisms is just as gigantic, rich and complex as the plant and animal kingdoms.
分類學上，地球生命不再侷限動物界、植物界，而加上真菌、細菌、原生動物等微生物共組成「五界」，每一微生物世界都與動植物世界一樣豐富龐雜。