FORCING THE MUSHROOM IN BRITISH GARDENS. 523 



sunny weather is frequently as high as 80. Whilst such hot weather 

 continues, mushrooms are rarely met with ; but when the atmosphere 

 changes to a humid state, and when the earth becomes sufficiently 

 moistened and lowered in temperature, in consequence of rain and 

 absence of sun-heat, to be between 60 and 65, mushrooms become 

 plentiful. Hence it may be concluded that spawn will not be injured 

 by a heat of 80 during what may be termed its underground state of 

 progression. This is corroborated by the fact that spawn introduced 

 into melon-frames when the beds are moulded, increases whilst the 

 melons are grown in a heat of about 80 ; and when the melon crop 

 is over, the frame cleared, and the heat of the bed naturally abated, a 

 gentle watering, with shade, is all that is necessary to bring up an 

 excellent crop of mushrooms from the spawn so deposited. It is 

 evident, from what has been stated, that the spawn requires a high 

 temperature for its diffusion ; but, when this has taken place, a declin- 

 ing temperature is requisite, till gradually the bottom heat is lowered 

 to 60 or 65, and the temperature of the air limited between 55 and 

 65, when the mushrooms first appear above the soil. 



" With regard to moisture, it may be observed that a dry atmosphere 

 is injurious, not only to artificial crops, but also to those in the fields ; 

 for the latter, warm foggy mornings are most favourable, and these 

 should be imitated as closely in cultivation as circumstances will 

 permit. A gentle steam is more easily maintained in mushroom- 

 houses than in structures adapted for other subjects of cultivation 

 where light is an object of importance : but mushrooms do not require 

 its agency, and consequently a glass roof is unnecessary : on the 

 contrary, the roof and walls where they are intended to be grown 

 should be composed of such substances as will cause the least possible 

 condensation of the internal vapour, and which are in other respects 

 eligible for the purpose. 



*' A thatched roof of a good thickness is very proper ; a slated or 

 tiled one is, on the contrary, objectionable, unless a ceiling be formed 

 under it. If the cavity between the ceiling and the external covering 

 were filled with dry moss, a more complete protection would be formed 

 against any sudden vicissitudes of cold and heat, an object of impor- 

 tance towards success either in the cold winter months or during the 

 greatest heat of summer." ('Penny Cyc.,' vol. xvi. p. 19.) 



Forcing the Mushroom in British Gardens. 



The ordinary form of a mushroom-house is a lean-to shed, at the 

 back of a south wall, or of a range of hothouses, about nine feet wide, 

 eight feet or nine feet high at front, and twelve feet or fifteen feet at 

 the back. Along the middle there is a path three ieet wide over a flue, 

 or hot water-pipes, or in some cases a trench of two feet wide, and the 

 same depth, for a bed of fermenting manure. Planks, in this latter 

 case, are placed over the dung for the purpose of walking on. The 

 space between the walls and the path is occupied by shelves of slate or 

 Hag-stone, three feet broad, eighteen inches or two feet apart in the 



