Other insects are not derived from living parentage, but are generated spontaneously: some out of dew falling on leaves, by nature in spring time, but not seldom in winter too when there has been a stretch of fair weather and southerly winds; others grow in decaying mud or dung; others in timber, green or dry; some in the hair of animals; some in the flesh of animals; some in excrements: and some from excrement after it has been voided, and some from excrement yet within the living animal, like the intestinal worms.