MUSHROOMS 409 



under its streets and properties, is the center of this great 

 mushroom industry. Subterranean quarries near the city 

 contain immense plantings, thousands of beds. In fact, 

 the quarries are responsible for the tremendous develop- 

 ment of this enterprise in France. The underground 

 chambers are extremely variable in shape and dimen- 

 sions. They may be 5 to 20 feet or more in height and 

 width, and they may have entrances which are easily 

 accessible, or it may be necessary to provide narrow 

 openings above the quarries, with windlasses for the 



Fig. 148. A modern commercial mushroom range at Kennett Square, Pa. Built of 

 concrete and tile. Frostproof and fireproof. 



handling of manure and other materials. Ventilation is 

 provided by means of special openings or ventilating 

 devices of various descriptions. 



In England, caves, cellars and specially constructed 

 houses are employed. In the United States, the bulk of 

 the commercial crop is grown in special houses such as 

 are shown in Figs. 147, 148 and 149. The majority of 

 the American mushroom houses are cheap, wooden struc- 

 tures, but in recent years more expensive buildings have 

 been erected by experienced growers. Wood is unques- 

 tionably the most common material used in the construc- 

 tion of American mushroom houses, although many 

 growers are employing the more durable materials, such 

 as tile, brick and concrete, with air chambers in the walls. 

 In most instances the houses are comparatively narrow, 



