and Laboratory Methods. 2111 



the best species for use in the germination of these spores are the ash rust, 

 the blackberry rust, and the rusts of the verbenas and the euphorbias. The 

 barberry rust is very good, but it cannot often be obtained. Uredospores 

 can, of course, be easily obtained in great abundance all through the summer 

 on the grains and grasses. The best material and most easily obtained, of 

 course, is found ordinarily on the cereals. The three spore forms just 

 mentioned, of course, occur mainly during the summer and are often called 

 summer spores. By wide observation we soon learn, however, that many of 

 these can be very easily obtained during the winter, and the spore cultures 

 can, therefore, be carried on the year round very readily. Uredospores from 

 the grains, and many of the grasses, can be obtained practically every month 

 of the year in almost all latitudes of this country. One needs, however, to 

 become familiar with their habitats and, therefore, be able to trace their 

 existence throughout the winter. In certain species, even aecidiospores can be 

 obtained fresh every month in the winter and germinated. This is particularly 

 true of Aecidum tiibcniilatiim Ell. and Kell., found in several of the Great Plains 

 states. Spores have been obtained by the writer from this species on plants 

 growing in the snow, and easily germinated. 



Teleutospores, with respect to the time and manner of germination, may be 

 divided into two general classes, although they are still further divided in 

 ordinary classification., These two classes are, (1) those that germinate 

 ordinarily at the end of the winter season, and (2) the lepto forms or those 

 which v/ill germinate ordinarily at once after their formation. The rust of 

 velvet leaf (abutilon) is a very good example of a lepto form that is easily 

 obtained in many parts of the country and very easily germinated. Teleutospores 

 of this rust can be germinated, the cultures applied to young plants of the same 

 host, and, after infection, material can be taken from the newly diseased leaves 

 and used in inoculating other plants, and the process repeated over and over 

 again inside of a few weeks' time. 



The ordinary stem rust of wheat and oats {F. graminis), the black rust of 

 sunflowers and the black rust of wild roses are good examples of those common 

 forms in which teleutospores germinate ordinarily at the end of the season. 

 There are sometimes exceptions, however. The writer has taken teleutospores 

 from the sunflower rust in October which were developed the same season, and 

 produced germination at the time without any period of rest whatever. The 

 germinating spores were even used for infecting sunflower seedlings and the 

 usual spermagonia followed by aecidia were produced. Such facts as these, in 

 connection with known instances where a^cidia have been found closely associated 

 with what were supposed to be lepto forms, show that we may occasionally be 

 in error in our classifications. Germination studies, therefore, as will be readily 

 seen, often throw much light upon the problem of classification. 



Of the genus Uromyces, the species found on Lespedeza, the wild bean, and 

 on certain grasses, especially Sporobuliis, are very good for a beginning of 

 germination studies with teleutospores. In order to successfully germinate 

 teleutospores after the winter resting period, I probably need not state that the 



