Arthur: Cultures of Uredineae in 1908 235 



mountains intervening; while the Nevada station is within two 

 hundred miles of the Pacific coast, and between it and the Ne- 

 braska station intervenes the great expanse of the Rocky Moun- 

 tains. 



The chief question demanding solution was whether this re- 

 markable heteroecious rust, which forms aecia on many species 

 of hosts belonging to the families Cruciferae, Chenopodiaceae 

 and Capparidaceae, has developed biological differences, as pre- 

 vious work had indicated. 16 In all thirty sowings were made. 

 A few of these proved failures because the plants used as hosts 

 did not grow well. The important results may be given without 

 recording all the data. 



The collections from the Atlantic coast, the first reported from 

 east of the Mississippi river, were made by Mr. H. S. Jackson, at 

 Lewes, Del., Nov. 16, 1907. Aecia were taken the following 

 spring in close proximity on seedling plants, which were fruited 

 in Lafayette, and ascertained to be A triplex hastata. Ten sow- 

 ings were made from these collections, using Cheno podium album, 

 C. hybrid 'um, Iva f rut esc ens on which in the same locality aecia 

 had also been found the following spring, and Decodon verticil- 

 latus, with infection only on Cheno podium album, which was 

 abundant. 



The mid-west collections were made, one by Rev. J. M. Bates, 

 at Red Cloud, Neb., and the other by Mr. R. E. Stone, at Lincoln, 

 Neb. These were sown on Cheno podium album, C. hybridum, 

 Sarcobatus vermiculatus, Monolepis Nuttalliana and Cardamine 

 bulbosa, with infection only on the first-named species. 



The far-west collections were made by Prof. P. B. Kennedy, 

 at Reno, Nev. They were sown on Cheno podium album, Atriplex 

 hastata and Sarcobatus vermiculatus, at three different dates, 

 fourteen sowings being made. Abundant infection resulted for 

 ' all the hosts ; nine plants giving equally vigorous results, the other 

 five not thriving well. 



These results taken with those of 1906 and 1907 show that no 

 marked biological differences exist. The only indication of re- 

 stricted adaptation is the failure to infect Sarcobatus from 

 Nevada with teliospores from Nebraska, although, as predicted 



18 Jour. Myc. 13: 197. 1907, and 14: 15. 1908. 



