MORPHOLOGY AND DEVELOPMENT OF AGARICUS 



RODMANI 



(Plates VII.-XIII.) 



By GEO. F. ATKINSON. 



(Read April 23, 19 15.) 



Introduction. 



Agariciis rodmanP- was described by Peck in 1885, from speci- 

 mens growing in " grassy ground and paved gutters " at Astoria, 

 Long Island. As to its habitat and occurrence a more specific state- 

 ment is made in 1897, in that it " grows in grassy ground and even in 

 crevices of unused pavements and paved gutters in cities,"^ from 

 May to July, and is said to be rare. It has been observed in the city 

 of Ithaca, N. Y., for a number of years, where it is usually found 

 growing in the parking between the sidewalks and street curbing, or 

 even in the crevices of stone paved streets and gutters, and also in 

 grassy ground along the street railway or along walks on the border 

 of groves. The material for this study was collected in August, 

 1914, along the Ithaca street railway and by the side of paths along 

 the border of groves on the campus. In these places the mycelium 

 in spots was often very abundant so that lumps of soil resembling a 

 fine quality of spawn were exposed in digging for the young stages. 

 The young fruit bodies collected were scattered on these cords of 

 mycelium, the material and conditions offering very clear evidence 

 of the normal development of the basidiocarps. The material was 

 fixed in chrom-acetic fluid and sectioned in paraffin. 



The features of interest in the morphology and development of 

 Agaricus rodniani which I have considered in the present study are 

 as follows: (i) the duplex character of the annulus, or ring, on the 

 stem, and its significance; (2) the origin of the hymenophore funda- 



iN. Y. State Mus. Nat. Hist. Kept., 36, 45, 1885. 

 2 N. Y. State Mus. Nat. Hist. Rept., 48, 139, 1897. 



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