noun
theory of spontaneous generation
Historical biological theory that living organisms can arise from nonliving matter. Now discredited.
パスツールの実験は自然発生説を否定した。
Pasteur's experiment disproved the theory of spontaneous generation.
Refers to spontaneous generation as a phenomenon, while 自然発生説 is the theory about it.
Compound of 自然 (nature) + 発生 (generation) + 説 (theory).