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fusca (Pers.) Wint., whose morphological aspects were strikingly similar to 
those of the Aecidiwm, i. e., the sori of the two rusts were arranged in the 
same manner; the effects on the host plant were the same, and the macro- 
scopic characters of the two were alike. He concluded that the two forms 
were closely related phylogenetically. Then his problem was: How find 
the alternate stage of the Aecidium form? 
On examining the teliospores of the short-cycled form microscopically 
he found them to possess very striking features, having a roughly warty 
wall, and being strongly constricted at the septum. A careful examination 
of his unconnected Puccinias revealed one having spores similar to those of 
the short-cycled form on Anemone, Puccinia Pruni-spinose Pers., the plum 
rust. He cultured the seciospores from Anemone on the leaves of plum and 
peach trees and grew the uredinia and telia of the plum rust. In his inves- 
tigations at this time he combined, in this way, five hetercecious species. 
Three of these species he proved by cultures; namely, 
1. Puccinia Prini-spinose Pers. with Aecidium punctatum Pers. 
2. lUromyces Veratri (DC.) Schroet. with <Aecidiwm Adenostylis 
Sydow. 
3. Uromyces Rumicis (Schum.) Wint. with Aecidium Ficarie Pers. 
The correlation, then, of two rusts of distinct species depends upon 
several things: first the family relationship of the host plants. The rusts 
are usually on the same or closely allied species of host plants. The macro- 
scopic characters of the two rusts are also of decided importance. They 
can usually be expected to have similar effects on the common host plant; 
and the location and disposition (i. e., whether they are amphigenous, 
epiphyllous, hypophyllous, Caulicolous; numerous or few, scattered or 
crowded; circular, oblong or irregular, ete.) of the sori are important 
factors. 
The most important thing, however, is the agreement of the microscopic 
characters of the analagous spore forms. The teliospores of the short- 
cycled and long-cycled forms are compared for thickness, color and mark- 
ings of the walls; the condition of the apex (thickened or not) ; measure- 
ments of the spores; length, color and type of pedicels; and the general 
conformation of the spores. 
Owing to the fact that the knowledge of the rust fungi of very many 
regions is not complete, the geographic distribution can not be considered 
aus extremely important. Nevertheless many interesting comparisons are 
shown by a study of the distribution of the correlated forms. 
