MUSHROOMS 291 



fungi, that is, plants living either as saprophytes upon decaying 

 organic matter or as parasites upon living vegetable growths. 

 While there is a great variety of so-called mushrooms, the only 

 one extensively grown commercially is Agaricus campestris. 



Propagation. The mushroom is propagated from vegetable parts 

 known as spawn, which are really the subterranean parts of the 

 plant known to botanists as the mycelium. The mycelium is 

 induced to develop to a certain stage in a suitable matrix or ma- 

 terial, such as stable manure and earth, and as soon as it is in proper 

 condition its development is checked by drying the material in 

 which it is growing. This material containing the dormant mycelial 

 threads of the mushroom constitutes the commercial mushroom 

 spawn. There are two types of spawn on the market that made 

 in brick form and known as English spawn, and that known as 

 French spawn, which is loose and strawy in texture. Until a few 

 years ago all spawn used in this country was imported, most of it 

 being of the English type, but within recent years high-grade 

 spawn has been manufactured in America. 



Culture. The conditions congenial to the development of the 

 mushroom are quite different from those required by green plants. 

 The mushroom has no green parts, or chlorophyll, and therefore 

 does not require light to carry on its normal functions, as do all 

 green plants. While the mushroom will expand in the light, it does 

 not require it. As a consequence its cultivation is largely carried 

 on in sheds, cellars, caves, etc., where moisture and temperature 

 conditions can be made congenial, but where no other type of 

 gardening would be possible. Special pits and dark sheds are 

 constructed in the vicinity of some of our large cities for the ex- 

 press purpose of growing this crop. In some localities abandoned 

 mines are employed, as are also cellars and pits. 



The requirements for success with this plant are (i) stable 

 manure, chiefly from horses, which has not entirely lost the power 

 of fermentation ; (2) a constant mild temperature of about 65 to 

 70 F. ; and (3) a moist atmosphere. In the moist climate of 

 England it is possible to produce a crop successfully by ricking the 

 manure in the open, as shown in figure 108, but this method is not 

 to be depended upon in this country. In some seasons it will suc- 

 ceed, but the chances of failure in the eastern United States are 



