398 



CLASS BASIDIOMYCETEAE 



The transfer of the production of the mycehum back from the teho- 

 spore to the aeciospore has apparently taken place independently several 

 times so that the microcyclic rusts of the formula 0, I are not necessarily 

 closely related but have probably developed in separate lines from 0, I, 

 II, III forms. It is clear that Kunkelia nitens, the microcyclic orange rust 

 of Ruhus, is derived from Gymnoconia peckiana, a long-cycle form (0, I, 

 III) on the same hosts. The genus Endophyllum represents a similar series 

 of cases. Some of the species of this genus correspond in aecial host and 



Fig. 131. Subclass Teliosporeae, Order Uredinales, 

 Family Pucciniaceae. A-D, Endophyllum sempervivi (A. 

 & S.) de By. (A) Binucleate aeciospore. (B) Aeciospore with 

 the nuclei united. (C) Aeciospore germinating. (D) Pro- 

 mycelium formed. (E, F) Endophyllum euphorbiae- 

 sylvaticae (DC.) Wint. (E) Aeciospore germinating with- 

 out union of nuclei. (F) Promycelium and sporidia. (After 

 Moreau and Moreau: Bull. Sac. Botan. France, 66:14-44.) 



structure to the aecial stage of known macrocyclic species. These abbrevi- 

 ated forms may even lack the fusions of the two nuclei within the spores 

 before the formation of the promycelium. Dodge and Gaiser (1926) 

 showed that in Kunkelia nitens the two nuclei pass out into the promy- 

 celium where each divides again to form the four nuclei which enter the 

 sporidia. The Moreaus (1919) have found the same to be true for Endo- 

 phyllum euphorbiae-silvaticae Lev., but in other species of the genus they 

 demonstrated nuclear fusion in the aeciospore before the promycelium 

 began to be formed. Dodge (1924) reported that in one form of Kunkelia 

 nitens no dicaryon mycelium was produced at all and the aeciospores re- 



