WHERE TO GROW MUSHROOMS 



sive array of artificial caves, especially un- 

 der Paris or in its environs. These caves 

 are indeed responsible for the enormous de- 

 velopment of the mushroom industry in that 

 country. Parisian buildings have been 

 constructed, in the main, of a limestone 

 w^hich has been mined under the city itself, 

 or in the adjacent suburbs and country. 

 The mining operations have been so con- 

 ducted as to leave vast labyrinthian systems 

 of caves. The caves now lying under the 

 city proper, known as the catacombs, are 

 not used for mushroom propagation. 



The suburban caves are from a few feet 

 to 50 feet beneath the surface. They vary 

 usually from 5 to 25 feet in width, excep- 

 tionally 50 feet, and from 5 to 20 or more 

 in height. The extent of these cave areas 

 is very great; and in many suburbs, such as 

 Montrouge, Vitry, Chatillon, Isny, Nan- 

 terre. Rosny-sous-Bois, Pasey, etc., mush- 

 room growing is one of the really important 

 industries. It has been estimated that in 

 the caves of the suburbs referred to, there 



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