270 



Mycological Bulletin Nos. 67 and 68 



[Vol.VI 



The writer does not intend to discuss even in a general way the relation- 

 ships of the various forms of Agaricus — that is, those that may be con- 

 sidered allies of A. campcstris — which he has cultivated or studied in the 

 field. Some reference to the variability of common forms should, however, 

 be made. For a comprehensive study of species and varieties, a knowledge 

 ot European forms as well as of those found in America is essential. Au- 

 thors differ so widely in their descriptions of species, as well as in theit 

 conceptions of them, perhaps, that in the absence of unlimited material 

 nothing short of confusion results from any attempt to harmonize opinions. 

 It is sufficiently difficult to separate what many would regard as varieties 

 of A. campcstris from those of A. ancnsis. When specific rank is be- 

 stowed also upon such forms as A. prateusis, A. inllaticus, A. maguificus, 

 A. rodniani, etc., the difficulties are greatly increased. The writer has 

 grown many forms of Agaricus, and, as might be expected, there seems 

 to be no form which will remain practically constant under variable con- 

 ditions. 



Imk. ~'ii!i. Tlic Oyster Mushroom (Pleurotus ostreatus), Growing on Decayed 

 Willow Log. From Hulletin No. 8.5, H. M. Duggar, Bureau of Plant 

 Industry, U. S. Department of Agriculture. 



[It might be added that stimulated by Dr. Duggar's work, several 

 firms have undertaken to furnish spawn prepared ui'der conditions that 

 would seem to guarantee success — yielding desirable "varieties" of Mush- 

 rooms. Tests by various amateurs and others show that the claims made 

 by these firms cati at least sometimes be verified. — Editor.] 



