PROTOBASIDIOMYCETES 397 



advances. These spores are 20-35 X I 5~ 22 A t > and a spore ger- 

 minates by the production of the characteristic promycelium, di- 

 vided ordinarily into four cells, each producing its sporidium. The 

 germination of the teleutospore would seem to take place ordinarily 

 several weeks prior to the appearance of the spermogonium and 

 aecidium, both of which arise only from teleutosporic infection. 

 The failure of the spermogonia and aecidia on red clover, pre- 

 viously referred to, may also indicate that the teleutosporic form 

 does not so readily infect this species of host. 



FIG. 196. UROMYCES APPENDICULATUS: RUST OF BEANS. (Photograph by 

 H. H. Whetzel) 



As a rule, control measures seem to be unnecessary ; at any rate 

 no practical preventive methods are known. 



V. RUST OF BEANS 

 Uromyces appendiculatus (Pers.) L^v. 



DE BARY, A. Recherches sur le deVeloppement de quelques champignons 

 parasites. Ann. d. Sci. nat. Bot. (SeV. 4) 20: 68-99. 1863. 



WHETZEL, H. H. Bean Rust. Cornell Agl. Exp. Sta. Built. 239 : 298-299. 

 figs. 113-113. 1906. 



This fungus is widely distributed, occurring on the bean (Phaseo- 

 lus vulgaris) and other related species. It is also reported in south- 

 ern latitudes on relatives of the cowpea, such as Dolichos ornatus, 



