EXPERIMENTS WITH LEPTOUREDINEiE. 25 



At Lincoln, Nebr., a water-drop culture was made of Puccinia 

 vexans on March 15, 1898, resulting in a few germinations of theteleu- 

 tospores in three days. Long pronrycelia were produced, but no 

 sporidiola. None of the numerous amphispores present germinated. 



On September 29, 1899, all three spore forms were again found in 

 the grass plats at Manhattan. Living host plants were transferred to 

 Washington, D. C, and seedlings were started for further experi- 

 ments, when other duties intervened and the work could not be 

 continued. 



Certain facts concerning the relative abundance of the amphispores 

 and teleutospores in different seasons and localities seem to harmonize 

 quite well with the idea already expressed as to the function of the 

 former. If it is the work of the amphispore to carr}^ the species 

 through unusually severe cold or drought, then this spore form should 

 be relatively more abundant in dry periods and relatively more com- 

 mon to the westward and northward in the Great Plains. These con- 

 ditions are just what exist. The amphispore prevails almost entirely 

 in the Dakotas and in western Kansas, western Nebraska, and eastern 

 Colorado, and appears to have been more common in eastern Kansas 

 during a dry period of several years than during a wet period. At 

 the same time westward toward the mountains there is less chance for 

 an iEcidiuni to connect with the teleuto stage. 



EXPERIMENTS WITH LEPTO-UREDINEiE. 



It is generally supposed that teleutospores which are followed by 

 an aecidium germinate only after a considerable period of rest, usually 

 in earh r spring. As already mentioned under the discussion of sun- 

 flower rust, the writer germinated teleutospores of this species readily 

 in the autumn, and afterwards at different times during the winter. 

 This readiness of germination, apparentl} T at almost any date, is an 

 indication in itself of an alliance to the lepto species. But, more than 

 this, the autumn inoculations with material in which no uredospores 

 could positively be detected nevertheless were, in some cases at least, 

 followed first by spermogonia and then by the uredo! Of course occa- 

 sional uredospores that may have been overlooked could have produced 

 those few spots in which the presence of spermogonia was not certain. 

 Here, then, is further evidence of the lepto tendency of the species. 

 In addition, it is well known that the eecidium is rare and appears to 

 have no fixed time of occurrence. Now, only the omission of the 

 uredo is needed to make the rust a real lepto species. As it is, its 

 position is more nearly that of a Hemi-puccinia than of an autoecious 

 species. Experiments of this kind, united with critical field observa- 

 tions, thus throw much light upon classification as to group position, 

 as well as enabling us to connect stages. 



On the other hand, certain lepto species will be found to closely 



