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MUSHROOM SPAWN MAKING. 57 



sufficiently rigid to be immediately handled if necessary. By this 

 method, unless the compost has been in excellent condition, the bricks 

 are not so smooth as might be desired for commercial purposes. In 

 some instances they have then been subjected to a repress process, 

 an old repress brick machine being adapted for the purpose. In 

 such cases the bricks are made thicker to begin with. The second 

 method has been discontinued by some who at first employed it. 



Two methods are also employed in spawning : ( 1 ) The more com- 

 mon method is to insert into the brick near both ends a piece of the 

 virgin spawn obtained for the purpose. A cut is made Avith the 

 knife, the spawn inserted, and a stroke of the knife effectively closes 

 the surface. This must be done as soon as the brick can be readily 

 handled. (;2) The bricks are dried until merely moist throughout; 

 then, on being piled, nocules of spawn are placed between successive 

 bricks, a piece at each end. In either case the bricks are not piled 

 for the growth of the spawn until in good condition as to moisture 

 content. This should be determined not by the surface, but by the 

 interior of the brick. In the pile the surface will soon become moist. 

 When the first method is employed it is sometimes customary to 

 spread between the layers of brick in the pile a little moist manure 

 or sawdust. It has been determined, also, that the absolute mois- 

 ture content of the brick should be about 40 per cent, which is the 

 same as for the mushroom bed. Tests of the moisture content of 

 bricks growing well have varied from 35 to 47^ per cent. 



Occasional examination should be made to determine the tempera- 

 ture and the extent of growth. In order that the bricks may become 

 thoroughly penetrated, more than a month will usually be required. 



The most favorable conditions for the growth of the spawn are 

 practically the same as for mushroom growing. A fairly moist 

 atmosphere, maintained, if necessary, by spraying, and a more or 

 less uniform temperature (55° to G0° F.) are to be preferred. The 

 size of the piles will depend upon the other conditions; but if there 

 is any danger of considerable fermentative activity the bricks should 

 be so disposed as to permit perfect ventilation between two or more 

 adjacent rows. 



When the bricks are thoroughly '* run " they are dried under cover 

 before being shipped or stored in Indk, since in a moist brick the 

 spawn would continue to grow and would soon produce small mush- 

 rooms or else would become moldy. Well-penetrated bricks of spawn 

 are shown in Plate VII, figure 2. The areas of mycelial growth 

 should be evident to the eye. The growth should be moldlike, how- 

 ever, rather than composed of very large threads or fibers. 



The suggestion made in a previous publication that mushroom 

 spawn should be sold by the brick (with a uniform standard of size) 

 seems to have been adopted l)y American makers. The trade names 



