(4i°) 



June 15, 1865, after his paper had been sent to the printer he 

 received word from DeBary concerning his successful culture 

 with Puccinia graminis and Aecidium Berberidis. To Oersted, 

 therefore, as well as DeBary we are indebted for much of the 

 pioneer work with the heteroecious rusts. He was especially 

 concerned with the species of Gymno sporangium, following up his 

 earliest work with the demonstration of the life-history of "Gymno- 



forme in 1867. 



This early work showed such a new departure in development 

 that contemporary botanists scarcely ventured to accept such a 

 strange story and one can find skepticism even in the early writings 

 of some who are still living. It is, therefore, not surprising that 

 considerable time elapsed before additional work was done along 

 this line. It was about fifteen years before further cultures were 

 made with the cedar rusts by Hartig, in Germany, a little later by 

 Farlow and Thaxter in this country, and by Plowright in England. 

 Since that time this work has been further advanced by a number 

 of investigators, among whom may be mentioned Barclay, Shirai, 

 Fischer, Arthur, Yamada and Miyake, and others. 



Necessity of Cultures 

 The fact having been once established that some of these fungi 

 have their life-cycle divided into two distinct alternating phases, 

 which inhabit wholly different and unlike host plants, the necessity 

 of experimental cultures to supplement the former method of 

 observation and description becomes at once apparent. The 

 local association of any two such alternating phases in nature 

 may lead one to suppose that the phases are related, but it requires 

 actual cultures to show whether the supposition is correct or not. 

 A culture in which a spore from one phase on one host is sown upon 

 another host, and subsequently gives rise to a spore form of the 

 alternating phase, is the only conclusive evidence that the two 



phases a. 



re related and i 



represent differei 



it forms 



of the same 



organism. 



Cu 



LTURE AlETHODS 







At this 



point it may no 



t be out of place 



to descr 



ibe briefly the 



methods 



which have bee: 



n found most si 



iccessful 



in cultivating 



the specii 



es of Gymnospor 



angium. In the 



first ph 



ice it may be 



