MUSHROOM GROWING 



ever, it should be recognized that there arc 

 several species of Agaricus which vary so 

 little in their characteristics that especially 

 w^hen grown under the forced conditions 

 of mushroom production it is an extremely 

 difficult matter to find distinguishing char- 

 acteristics. Some would maintain that cul- 

 tivation has modified the natural species to 

 such an extent that they are not readily 

 recognized. It should be pointed out, how- 

 ever, that until recently the grower has 

 obtained his 'Virgin" spawn almost annually 

 from ^'spontaneous" occurrences of mush- 

 rooms in the field and pasture, or from 

 spawn appearing in the compost heap. 

 Therefore if there are many 'Varieties" in 

 cultivation, these same varieties must in 

 large part exist also in the open. I find it 

 difficult to agree with those who adhere to 

 the view that cultivated varieties have orig- 

 inated from wild varieties by mutation. 



I am convinced that there are from a half 

 dozen to a dozen distinct forms frequently 

 used in cultivation, and that these must rep- 



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