GYMNOSPORANGIUM WITH REPEATING SPORES 
45 
A few words only need be said to point out that the completion of 
the life-cycle of this one species makes a long stride forward in firmly 
establishing the theoretical basis upon which the classification of the 
Uredinales presented at Vienna in 1905 was constructed.^ That 
classification undertook to consider all rusts from the standpoint 
primarily of their life-histories, actual or potential, and secondarily 
of their comparative morphology. From lack of knowledge much 
had to be assumed, but as the passing years supply the desired informa- 
tion, the reasonableness of the original assumptions becomes more and 
more apparent. 
According to this classification all rusts are either short-cycled, 
having only one sporophytic spore-form, or long-cycled, having (i) 
a primary (aecial) spore-form, (2) a repeating stage, in some species 
partly or wholly suppressed, and (3) a final (telial) spore-form. The 
cedar-rusts presented a highly differentiated group, possibly the most 
specialized of all the rusts, in which no repeating-spores were known. 
So long as the repeating-stage was unknown, some doubt attached to 
the true position of the group in the classification, and even more 
doubt to the genuineness of the basic assumptions of the whole 
scheme. Bringing to light this primitive species of Gymnosporangium 
with its very active repeating stage is, therefore, a matter of moment. 
Purdue University, 
Lafayette, Indiana. 
^ Arthur, Eine auf die Struktur und Entwicklungsgeschichte begriindete Klassi- 
fication der Uredineen. Result. Sci. Congr. Bot. Vienna 331. 1906. 
