SELECTED CYCLES IN GYMNOCONIA PECKIANA 
George F. Atkinson 
At the present time Gymnoconia peckiana is one of the most inter- 
esting species of the rust fungi. As a result of Tranzschel's cultures 
it was generally accepted as a short-cycle species with two generations 
in the complete life history. A disquieting factor was introduced 
when Kunkel presented the results of his studies on the germination 
of the aecidiospores, demonstrating a still shorter cycle, since the 
aecidiospores germinated in the manner normal for teleutospores, i. e., 
by the production of promycelia and sporidia. 
This seeming contradiction in the diverse accounts of the life 
history of Gymnoconia peckiana was interpreted in different ways. 
Some students suggested that the aecidiospores could germinate in 
either one of two ways. First, under certain conditions they might 
germinate in the usual way for aecidiospores, by the production of an 
infection tube, forming a di-energed mycelium in the host, terminating 
in the formation of teleutospores, thus presenting a two- generation 
cycle. Second, under other conditions the aecidiospores might assume 
the functions of teleutospores by germinating with promycelium and 
sporidia, thus presenting a one- generation cycle, of course leaving the 
spermogones out of consideration. 
According to another interpretation, these two different cycles 
represented two distinct specific, or generic, entities. In these two 
entities, the aecidial stage of the one-generation cycle and the aecidial 
stage of the two-generation cycle were morphologically indistinguish- 
able, though specifically distinct. The morphological identity of the 
aecidial stage of both cycles has been demonstrated by Kunkel in a 
more recent paper, though I do not understand that he has expressed 
any opinion as to whether or not the one-generation form is specifically 
distinct from the two-generation form. 
A few years after Tranzschel's cultures, indicating the genetic 
connection of Caeoma inters titialis with Puccinia peckiana in Russia, 
as a matter of personal curiosity I transplanted to the greenhouse some 
raspberry plants which were free from the Caeoma. On these I sowed 
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