THE AECIDIAL STAGE OF PUCCINIA GRAMINIS PERS. 285 



the power of producing the aecidial stage on the barberry. 

 This may be true for teleutospores kept in hot dry districts 

 where they lose their power to germinate. But in some 

 cases at least the complete life-history of the fungus can 

 be gone through under Australian conditions. Further 

 work is planned to try and ascertain the conditions which 

 are requisite. 



The infections here recorded were obtained under 

 extremely artificial conditions. But careful observations 

 of barberry bushes growing in the cooler areas of the State 

 should be made to determine whether infection may not 

 also take place under natural conditions. 



European and American observations have shown that 

 the aecidial stage is of great importance in starting the 

 early rust attack of cereals. Further, recent work of Dr. 

 E. C. Stakman and his co-workers at Minnesota, U.S.A., 

 has led him to believe that the aecidial stage on the bar- 

 berry may be very important in multiplying the number of 

 biologic forms of the rust. His theory is that infection at 

 a spot of a barberry leaf may be brought about by sporidia 

 of two different biological forms. Each gives rise to a 

 uninucleate mycelium. It is possible that the two mycelia 

 may intermingle. In the derivation of the binucleate 

 aecidiospores at the base of an aecidium, one nucleus may 

 be contributed from each mycelium. Such an aecidiospore, 

 having a different nuclear constitution to that of aecidio- 

 spores of either of the two biologic forms, may be expected 

 to behave differently, and probably to constitute a new 

 biologic form. 



It has already been stated that no species of Berberis 

 are native to Australia but that barberry plants have been 

 distributed throughout the country. In view of the proof 

 that infection may be brought about, this distribution 

 should cease. It is true that the positive results were 



