208 



PROTOBASIDIOMYCETES 



[CH. 



the usual way. In the micro- form Puccinia transformans Olive observed 

 that the binucleate condition was brought about by the fusion in pairs of 

 cells to form the basal cells from which the teleutospores arose and the 

 same has been reported by Moreau for Puccinia Buxi and Uromyces Ficariae. 

 In Puccinia Malvacearum Moreau occasionally found a difference in size 

 between the fusing cells, and Werth and Ludwig observed the migration 

 of the nucleus of the smaller cell into the 'larger (fig. 184^). 



Below the teleutosorus of Puccinia Podopliylli also, Christman found 

 nuclear migrations in progress (fig. 184^). Such cases clearly suggest that 

 here, as in the mycelium below the aecidium of P. Poanim and in the 

 prothallus of pseudapogamous ferns, the sporophyte is initiated by the 

 association of two vegetative nuclei. Christman, however, observed that in 

 certain cases migration took place between cells already binucleate, and he 

 hence regards migrations in this case, and is inclined to regard all other 

 migrations in rusts, as due to pathological causes. 



^s&-x 



S.; migrations at base of teleutosorus; after Christman. 



A sporophytic stage of exceptionally brief duration is also found in the 

 species of Endophyllum and in the form on Rnbns frondosus known as 

 Kunkelia mtens\ In both cases the characteristic spores are developed in 

 basipetal chains (fig. 185), and in both the fertile cells which give rise to 

 them fuse in pairs (Olive '08; Hoffmann 'it), so that the spore mother-cells, 

 intercalary cells and spores receive two nuclei each. In Endophyllum the 

 spores are enclosed in a pseudoperidium of barren cells so that the sorus 

 appears as a typical aecidium, in Kunkelia nitens it is of simpler, indefinite 



1 Kunkelia nitens (Schwein.) Arthur = Caeoma nitens Burr. 



