EXrKKIMENT^^ WITH LKPTO-UREDINE.E. 25 



At Lincoln, Ncbr., a wiiter-drop culture was niadt^ of Piiccinia 

 ve.r(iiis oil March 15, lSt)S, resulting' in a few j>vrininatioiis of the toKni- 

 tosporcs in three chu's. Long pi'oniycelia were produced, hut no 

 sj>(»ridiola. None of the nuni(>rous aniphispores pre.sent germinated. 



On Septenil)er 2t>, ISlMt. all thrcM^ spore forms were again found in 

 the grass plats at Manhattan. Living host ])lants w(»re tninsferred to 

 Wiishington, D. ('., and s(M>dlings were started for further experi- 

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

 continued. 



Certain facts concerning the rehative al)undancc of the aniphispores 

 and teleutospores in different sea.son.s and localities seem to harmonize 

 quite well with the idea already expressed a.s to the function of the 

 former. If it is the work of the amphispoi-e to carry 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 (ireat Plains. These con- 

 ditions are just what exist. The amphisporc prevails almost entirely 

 in the Dakotas and in western Kansas, western Ne})raska, and eastern 

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

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

 the same time we.stvvard toward the mountains there is le.ss chance for 

 an ^T^^cidiuin to connect with the teleuto stage. 



EXPERIMENTS WITH LEPTO-UREDINE-ffi. 



It is generalh' supposed that teleutospores which are followed by 

 an fecidium germinate only after a considerable pei'iod of rest, usually 

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

 flower rust, the writer germinated teleutospores of this species readily 

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

 This readiness of germination, apparent!}^ 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 ma}- have been overlooked could have produced 

 th<jse 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 fecidium is rare and appears to 

 have no fixed time of occurrence. Now, only the omi.ssion of the 

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

 position is more nearl}'^ that of a Hemi-puccinia than of an auta^cious 

 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 



