1384 



ENCYCLOPEDIA OF PRACTICAL HORTICULTURE 



dustry. At present it is possible to re- 

 port greater success and a more practical 

 application of that work. It is now 

 possible by means of chemical stimula- 

 tion to germinate the spores in quantity 

 under "pure-culture" conditions. Un- 

 fortunately, at the present time it can 

 not be said that spore-culture methods 

 are unfailingly successful where the 

 pure-culture precautions are not ob- 

 served. It is confidently expected, how- 

 ever, that within the course of another 

 year it will be within the reach of any 

 practical and experienced grower to de- 

 velop spawn from spores of selected 

 mushrooms which he may have grown. 

 By these methods one will be able to se- 

 lect the particular mushrooms from 

 which spores are to be taken, and there- 

 fore constant selection and improvement 

 will become possible. 



^^Tissue-Culture'* Method 



Another line of development discov- 

 ered through work in the Department of 

 Agriculture yielded even better results 

 than the spore-culture process. It may 

 be termed the "tissue-culture" method, 

 and is described as follows: Test tubes 

 or large-mouthed bottles are filled with 

 fresh stable manure or with compost, 

 and after being plugged with cotton 

 these tubes are sterilized, the steriliza- 

 tion being best effected in a steam-pres- 

 sure apparatus. They can be sterilized, 

 however, by boiling for one-half to one 

 hour in an open vessel of water, but 

 when this process is used a second ster- 

 ilization should be given on the follow- 

 ing day. This will render these tubes 

 of compost perfectly free from all bac- 

 terial or fungous contamination. One 

 should then select from the growing bed 

 vigorous, well-flavored mushrooms of a 

 variety or race which has proved to be 

 unusually prolific. The specimens se- 

 lected should be large enough to indicate 

 that they have the characters desired. 

 The younger the specimen the better, 

 other conditions not being neglected. 

 With a sterilized scalpel and forceps one 

 may then break off the stem, peel off the 

 outer skin, and remove with great care 

 bits of the tissue of the mushroom with- 



out touching any surface which has not 

 been flamed. These bits of tissue may 

 be carefully inserted into the manure 

 in the sterilized tubes. In the course 

 of a week, or sometimes within three 

 days, if no accidental contamination has 

 resulted, these bits of tissue will be 

 found to have sent out a small growth 

 of mycelium. Under favorable condi- 

 tions this mycelium will spread to all 

 of the material in the tube or bottle 

 in the course of three or four weeks, 

 and it may then be used as pure-culture 

 virgin spawn. These cultures may be 

 made in milk bottles of considerable 

 size; or, once a few tubes have been 

 made, transfers from the mycelium of 

 these may be made to milk bottles con- 

 taining the sterilized compost, and thus 

 a considerable quantity of an absolutely 

 pure spawn may be produced to serve 

 as inoculation material for bricks or for 

 the flake spawn. It is unfortunate that 

 this method also involves, and must in- 

 volve, bacteriological precautions. Never- 

 theless, this process renders it possible 

 to select mushrooms of a given char-, 

 acter, or to select toward a given end, 

 with the same certainty with which we 

 may select the seed of other crops com- 

 mercially grown. Moreover, experi- 

 ments are now under way which will 

 undoubtedly show that by starting with 

 a few pure cultures this principle may 

 be applied for the production of spawn 

 in quantity. 



The ITanufacture of Brick Spawn 



The bricks should be solid and com- 

 pact and with no cracks or irregularities 

 in the surface. In order to secure bricks 

 of this kind and the best growth of the 

 mycelium, it has been found by experi- 

 ence that a mixture of manure from 

 the cattle shed and from the stable is 

 desirable. This is usually mixed in the 

 proportion of two-thirds of the former 

 to about one-third of the latter, a small 

 quantity of loam being sometimes added. 

 In making the bricks, the material 

 should be somewhat less composted than 

 for making mushroom beds, and it needs 

 to be well selected or raked over, since 

 too much straw in the brick will render 



