34 MUSHROOM CULTURE. 



litter is necessary for beds formed in the open air, and 

 also for beds made in cool, half-open sheds ; but not for 

 those in regularly heated mushroom-houses or caves, in 

 which there is a still, steady temperature. It should be 

 about a foot thick, and should be immediately removed 

 when it becomes wet or mouldy. This covering should 

 be applied whenever the temperature of the bed begins 

 to fall. It should not be used in any case where the tem- 

 perature will permit of dispensing with it, as it is trouble- 

 some, and sometimes encourages insects. The heat of a 

 bed may be reduced by opening holes six or eight inches 

 deep with a thick pointed dibber, here and there, but it 

 is only in exceptional cases that this is advisable, and it 

 is desirable to husband all the ammonia and heat of the 

 bed. The earthing over and firming of a bed has a ten- 

 dency to subdue the heat in it. Where large sloping 

 beds, say three feet deep at back, are made against the 

 wall, I have seen A-shaped crates put beneath them at 

 six feet apart, so as to permit of heating them by fresh 

 supplies of manure. It is, however, a plan possessing 

 little claim to general use. It is best not to depend on 

 the hand, as is commonly done, for ascertaining the 

 heat of the beds. Thermometers fixed on sticks of con- 

 venient size, to thrust in the beds, are sold, and remove 

 all excuse for vagueness in this matter. Coverings of 

 litter are sometimes useful in " drawing-up the heat" in 

 a bed that has become somewhat chilled. 



