377 



eiit, and thus shuwiiig detiiiitely that the two alternate phases on wholly 

 different plants belong to the same species of fungus. 



Thus a large number of aecia have been properly assigned to their 

 telial connection, and still many others remain to be thus connected. 



At first the species of Aecidiuin were placed in groups largely accord- 

 ing to hosts, but as they were studied more closely, both microscopically 

 and in cultures, it ^Yas found that often tliere occurred many forms on 

 the same family of host plants, and often on the same host genus, several 

 distinct species could be segregated. Even on the same liost-species it 

 was not infrequent to find more than one species of Aecidiuin. As cer- 

 tain of these aecia were properly referred to their telial connections, these 

 were separated as carefully as possible from the unattached forms and 

 flu- latter remained to be studied further. In certain cases the definite 

 morphological characters of the forms that are properly connected with 

 their telial stages have made it possible to segregate definitely the at- 

 tached forms from the unattached forms. In other cases where the mor- 

 phological differences are less distinctive, and where certain physiological 

 differences exist, the separation between the attached and unattached 

 forms lias been less definite, and in some cases it is impossible to make 

 such separation with certainty until further cultures are made in order 

 to help decide tlie matter. In making such separation of attached from 

 unattached forms it is clear then that it is necessary to take into con- 

 sideration not only the morphological characters of a species but also its 

 physiological behavior in cultures. 



It has been the purpose of this study to make such separation, farther 

 than it had already been made, and to determine as far as possible the 

 number of forms still unattached and to work out clues for probable con- 

 nection wherever possible. 



The forms of aecia whose telial connections still remain unknown, 

 are arranged and follow in the form of an annotated list preceded by a 

 provisional key, for convenience of reference. Under each species are 

 given as far as possible the citation of the original description and dat? 

 of publication, the hosts inhabited, the states and provinces in whicli the 

 species has been found on each host, the type locality, type host, general 

 distribution, and reference by number to siiecimens published in sets o'' 

 exsiccati. Notes follow in most cases, especially where the form is es- 

 pecially striking, or where there are clues to relationship, or where there 



