PROTOBASIDIOMYCETES 393 



Uromyces Rumicis (Schum.) Wint. Rumex spp. (sorrels) 



Hemileia vastatrix Berk. & Br. . . Coffea arabica (coffee) 



Puccinia Chrysanthemi Roze. . . Chrysanthemum spp. 



Puccinia Polygon* Pers Polygonum spp. 



Puccinia Allii De C Allium Cepa (onion) 



Microuredo (Stage III) 



Uromyces Solidagmts(Somm.}N\zss\. Solidago spp. (goldenrod) 



Puccinia Ribis De C Ribes spp. (currant, gooseberry) 



Puccinia fusca Relhan Anemone nemorosa, etc. 



Leptouredo (Stage III) . 



Puccinia malvacearum Mont. . . Althaea rosea (hollyhock), etc. 

 Puccinia Xanthii Schw Xanthium spp. (cocklebur) 



(Stages O, III) 

 Uromyces tepperianus Sacc. . . . Acacia spp. 



(Stages O, I) 



elatinujn Alb. & Schw. . Abies spp. (firs) 

 Grossularice Schum. . . Ribes spp. (currant, gooseberry) 

 Peridermium Engelmannii Thiim. Pinus Engelmannii 



(Stage II) 



Uredo Fid Cact Ficus carica (fig) 



Uredo Gossypii Sager Gossypium hirsutum (cotton), etc. 



During the past few years considerable activity has been mani- 

 fest in the study of the cytology and possible fertilization processes 

 in the Uredinales. It had been known since the studies of Sappin- 

 Trouffy and Dangeard that the binucleate condition of the teleuto- 

 spore and of the mycelium preceding it leads finally to a fusion of 

 these two nuclei preceding the development of the promycelium. 

 The recent studies have been directed primarily toward a knowl- 

 edge of the origin of this binucleate condition. Blackman in some 

 extensive studies of a caeoma stage, in particular, demonstrated what 

 he believed to be a fusion phenomenon in the following manner : 

 During the early development of this stage numerous gametic 

 branches arise. These come in contact in pairs, the older and 



