544 



COMPARATIVE MORPHOLOGY OF FUNGI 



Iola, mostly parasitic on moss sporophytes, continues the tendency 

 of Helicobasidium and Platygloea nigricans to store up reserves in the 

 zeugites which are developed to characteristic organs called probasidia. 

 The mycelium grows through the cap of the sporogonium, forming a 

 thick felt between cap and capsule and then penetrates the interior. 

 The hyphae are binucleate, septate and without clamps. At the surface 

 of the sporogonium (Fig. 364, 8, Sp) they form a felt which is relatively 

 loose in the Brazilian I. Hookeriarum (Moller, 1895). In I. javensis 

 (Gaumann, 1922), the hyphae are imbedded in a gel forming a small fruc- 

 tification like a drop of slime on top of the sporogonium (Fig. 364, 7, Sp). 

 The hyphae are slightly sinuate, being quite parallel to each other in the 



Fig. 363. — Iola javanensis. 1. Section of young hymenium. 2. Older stage, showing 

 the beginning of the formation of probasidia. ( X 375; after Gaumann, 1922.) 



extramatrical part in Fig. 363. Their ends become clavate, the two 

 nuclei approach and fuse (Fig. 364, 2 and 3). 



The zygote nucleus remains a short time in a resting state, then passes 

 over into the prophase. It migrates to the tip of the probasidium and 

 begins synapsis. Meanwhile a parallel branch is formed below the 

 primary probasidium, the dicaryon of the uppermost hyphal cell, the 

 subterminal cell, migrates to the top of the cell and divides conjugately. 

 One-half the daughter nuclei slip into the branch which again swells to a 

 probasidium and pushes aside the primary probasidium. The other 

 half remain in the hyphal cell where the formation of new probasidia 

 is repeated (Fig. 364, 3 to 5), finally resulting in the structure shown in 

 Fig. 364, 1 ; thus the whole development of probasidia rests in the dicaryon 

 of the subterminal cell. 



