AGARICALES 



465 



known. Superficially the fungus resembles an agaric but produces 

 sheets of biconvex bulbils in the place of lamellae. The mycelium 

 develops readily from bulbils on blocks of porous wood which are not 

 too wet. The stipe primordium of large and longitudinal hyphae is 

 early developed. The pileus is covered by a universal veil. Trabeculae, 

 the primordia of the lamellae, extend from the pileus to the ground 

 tissue, but no annular gill cavity is formed. The pileus becomes broadly 

 conical, the tissue between the pileus and the stipe begins to produce 

 bulbils, which arise singly, not in continuous sheets. They are of loose 

 texture at first, often hollow and lined with a palisade layer or, if solid, 

 with two opposed palisade layers in the center. The cells of the palisade 

 layers produce cylindrical or oval spore-like cells at their apices within the 



Fig. 295. — Rhacophyllus lilacinus. 



Caryogamy and plasmogamy in the bulbils. (After 

 Moreau, 1913.) 



developing bulbil. These cells do not become free but remain united 

 in short chains. The bulbils never include hyphae of the ground tissue 

 and at maturity are shed instead of spores (Petch, 1926). 



While in the normal agaric the gill primordia develop into plates of 

 tissue which produce palisade layers of basidia externally relative to the 

 primordial tissue; in Rhacophyllus the "gill primordium" or trabecula 

 develops a palisade tissue internally from either side, like the hymenium 

 of the Gasteromycetes. 



The bulbils contain mostly binucleate cells. The nuclei approach 

 and fuse (Fig. 295, 1 and 2), the resulting nucleus divides twice so that 

 there are four nuclei. Two of the four nuclei degenerate and the primitive 

 nu'clear number is restored. Thus the nuclear behavior is similar to that 

 of a basidium (Moreau, 1913). 



Often the septa dissolve and the protoplasts fuse (Fig. 295, 7 and 8). 

 The material on which these studies were based was such that further 

 details were not obtainable. Here apparently we have groups of basidia 

 (or perhaps spores) taking the place of normal basidiospores in reproduc- 

 ing the organism. The relationships of this genus are very obscure. A 



