i$o TEXT-BOOK OF FUNGI 



period, however, teleutospores are alone present. The 

 production of teleutospores completes the cycle of develop- 

 ment of the fungus. The following spring the teleutospores 

 germinate, infection of the barberry follows, and the cycle 

 of development commences anew. 



Pucdnia graminis is a very injurious parasite to cereals, 

 and at one time it was thought that if the cycle of develop- 

 ment could be broken by removing one of its host-plants 

 the barberry the disease would be arrested. This line 

 of reasoning unfortunately has not proved to be correct. 

 The fungus is capable of going on as usual when the 

 aecidium stage has been eliminated from its cycle of 

 development. This fact does not support the view 

 recently announced that the aecidium condition gives a 

 stimulus to the general development of the fungus. In 

 some species of the Uredineae the teleutospore stage 

 alone is present, as in the hollyhock rust (Pucdnia 

 malvaccarum). The aecidial stage has dropped out in 

 many species. 



De Bary, Neue Unte^s. u. Uredineen^ Monatsbr. d. Berlin 

 Akad.j Jan. 1865 and Apr. 1866. 



MYCOPLASM 



Eriksson has arrived at the conclusion that the sudden 

 and widespread epidemics caused by the rust fungus of 

 wheat are not entirely due to external infection of the host 

 by spores dispersed by wind and other agents. The theory 

 is advanced that in certain varieties of wheat, more 

 especially the form known as ' Horsford pearl,' the proto- 

 plasm of the rust fungus is present, mixed with the proto- 



