Spontaneous generation or anomalous generation is an obsolete body of thought on the ordinary formation of living organisms without descent from similar organisms. Typically, the idea was that certain forms such as fleas could arise from inanimate matter such as dust, or that
The doctrine of spontaneous generation was coherently synthesized by
Pasteur's experiment is generally agreed to have decisively refuted the theory of spontaneous generation in 1859.
 Disproof of the traditional ideas of spontaneous generation is no longer controversial among professional biologists. By the middle of the 19th century, the theory of
Spontaneous generation refers both to the supposed processes in which different types of life might repeatedly emerge from specific sources other than seeds, eggs or parents, and also to the theoretical principles which were presented in support of any such phenomena. Crucial to this doctrine is the idea that life comes from non-life, with the conditions, and that no causal agent is needed (i.e. Parent). Such hypothetical processes sometimes are referred to as abiogenesis, in which life routinely emerges from non-living matter on a time scale of anything from minutes to weeks, or perhaps a season or so. An example would be the supposed seasonal generation of mice and other animals from the mud of the Nile.
 Such ideas have no operative principles in common with the modern hypothesis of
Another version of spontaneous generation is variously termed univocal generation,
In the years following