PROTOBASIDIOMYCET1 S 



393 



Rut/n't is (Schum.) Wint. Rumex spp. (sorrels) 



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



Puccinia Chrysanthcini Roze. . . Chrysanthemum spp. 



Puccinia Polygoni Pers ..... Polygonum spp. 



Puccinia Allii De C ...... Allium Cepa (onion) 



Microuredo (Stage III) 



I r romyccs Solidaginis (Somm.) Niessl. 



Puccinia Ribis De C 



Puccinia fusca Relhan 



Solidago spp. (goldenrod) 

 Ribes spp. (currant, gooseberry) 

 Anemone nemorosa, etc. 



Leptouredo (Stage III) 



Puccinia niali>aceanini Mont. 

 Puccinia Xc:nthii Schw. 



Althaea rosea (hollyhock), etc. 

 Xanthium spp. (cocklebur) 



(Stages O, III) 

 Uromyces tepperianus Sacc. . 



(Stages O, I) 



sEcidiuni elatinuni Alb. & Schw. . 

 ^Kcidiuni Grossularics Schum. . 

 Peridermium Engelmannii Thiim. 



(Stage II) 



Uredo Fid Cact 



Uredo Gossypii Sager 



Acacia spp. 



Abies spp. (firs) 



Ribes spp. (currant, gooseberry) 



Pinus Engelmannii 



Ficus carica (fig) 



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 



