EMERGENCY ADAPTATIONS. 21 



Henn. yet found in this country. The known hosts are Elymus cana- 

 densis and E. virginicus, but it seems to occur on other hosts. Whether 

 the forms on different hosts can be transferred from one to another 

 is not yet fully determined. 



The important fact now known, however, is that the uredoform is 

 able to preserve the species over the winter without the intervention 

 of other stages, though it is possible that extensive propagation is 

 aided by other stages. October 28, 1897, fresh uredosori were observed 

 on Elymus canadensis at Manhattan, Kans., and again in the same 

 locality on November 2. But as early in the spring as May 26, at 

 Lincoln Nebr., when there was yet but a small beginning of vegetation, 

 the uredo had burst the epidermis of the host in grass plats at the 

 University farm. Previous to this the living uredo had been observed 

 in these plats practically every month of the winter. 



In other instances the uredospores of certain species are so very 

 abundant and the teleutospores so rare that there seems a probability 

 that such species are carried over from summer to summer largely 

 through the uredo stage alone, though there is no absolute proof of 

 such a course. Two instances are particularly interesting — those of 

 the uredos of Puccinia cryptandri Ell. and Barth., and Puccinia on 

 Panicum autumnale. 0. The uredospores of these species begin to be 

 conspicuously abundant about midsummer, but continue in consider- 

 able abundance until very late in autumn. The uredo of Panicum 

 autumnale was found in germinating condition in Kansas up to Novem- 

 ber 3 in 1897. A water-drop culture of uredospores of this species 

 gave excellent germination in ten hours August 21, 1897, at Perkins, 

 Okla. The uredospores of Puccinia cryptandri were found in extreme 

 abundance in Oklahoma until October 11, 1897, but in all cases with- 

 out any accompanying teleutospores. Often the uredosori had a fresh 

 appearance on portions of leaves that were quite dead. 



EMERGENCY ADAPTATIONS. 



In connection with some culture experiments conducted at Lincoln, 

 Nebr., in the botanical laboratory of the State University, in Februaiy, 

 1898, a water-drop culture was made (Februaiy 3) of uredospores of 

 the above-mentioned Puccinia cryptandri which had been collected on 

 October 8, 1897, at Perkins, Okla., and kept to date as herbarium 

 specimens. A fair germination resulted in twenty-four hours. Spores 

 from the same collection were used on February 16 to inoculate seed- 

 lings of Sporobolus airoidesf with the result of the appearance of two 

 rust spots by March 16. These spots may really have appeared much 

 earlier and been overlooked, as they were very small and the host 



a Perhaps a new species, needing further study. 



b Apparently this same species of rust had already been collected on Sporobolus 

 airoides in the same locality where the collection from S. cryptandri was made. 



