"In France the mushroom industry has fallen heir to the subterranean quarries which now constitute a very extensive array of artificial caves especially under Paris or in its environs. ...In the caves of the suburbs mushrooms are so commonly grown that "champignonière" (mushroom cave) is practically synonymous with "carrière" (cave). The cave systems are very well ventilated by means of chimneys or chutes. The change of air is often facilitated by small charcoal fires beneath these air chutes and occasionally by the use of special ventilating devices."