236 MYCOLOGY 



annular zone of new growth toward the upper part of the young fruit 

 body (basidiocarp) and with its origin the four primary parts of the 

 basidiocarp, pileus, stem, marginal veil and hymenophore are differen- 

 tiated. By the continued growth and multiplication of hyphae rich in 

 protoplasm, which are parallel and directed downward, the hymeno- 

 phore primordium becomes more compact to form a level palisade 

 zone, and as the ground tissue beneath lags behind in growth, the more 

 rapid growth of hymenophore causes a rupture of the ground tissue 

 beneath and an annular gill cavity arises. The lamellae project into this 

 cavity, as downward-growing radial salients of the level paUsade zone, 

 beginning next to the stem and proceeding in a centrifugal direction. 



Cultivation of the Mushroom. — The commercial growing of mush- 

 rooms has been placed upon a sure financial basis within recent years 

 and around Philadelphia, notably in Chester County, there are large 

 concerns which make the culture of mushrooms a specialty. Mush- 

 room cultivation is an important business in Europe, especially in 

 France where certain of the grades are canned and bottled for export 

 trade. Mushrooms are grown in America in long mushroom houses, 

 or sheds especially constructed and heated for the purposes of the trade. 

 Cellars are also devoted to the industry. Sometimes they are grown 

 under the benches of greenhouses devoted to the raising of other plants. 

 The beds are so constructed of boards that they rise in tiers of four, or 

 five with a central aisle, or in the larger houses there are tiers of beds 

 along the walls and in the center of the house with two aisles running 

 lengthwise with a cross aisle at the far end or in the middle of the house. 



Stable manure is used as the compost for comm.ercial mushroom 

 culture. Bedding straw should also be included with the manure in 

 the compost. The manure should be the best that can be obtained. 

 It should be thrown into piles about four feet high and forked over 

 occasionally to assist the fermentation process, which is assisted further 

 by wetting the fermenting mass occasionally until the fermentation is 

 completed, which is usually at the end of three weeks. During this 

 time all objectionable odor should be lost and the temperature should 

 decline to 120° or I30°F. Out of this compost the beds are constructed 

 by compressing the mass with blows of a spade, or by a compressing 

 board. Growers cover the manure bed with a thin layer of garden soil 

 one to one and a half inches deep. This operation is known as casing, 

 and is performed after the spawning operation has been completed. 



