Sept. 1907] Cidhires of Ureditieae in ipo6 199 



year's cultures the opinion was expressed that this rust may be 

 composed of biological races, but the present work shows that 

 adaptation to the hosts is not so close but that under specially 

 favorable conditions the rust may be transferred from one host 

 to another. 



i6. PucciNix\ Pruni-spinosae Pers. — Aecia on Hepatica 

 acutiloba DC, from near Lafayette, Ind., were sown April 28 

 on Prunus scrotina and Amygdalus Per ska, giving rise May 21 

 to uredinia on the former host, but with no infection on the lat- 

 ter host. Like material was sown May 2 on Prunus serotina and 

 P. puniila, giving rise to the uredinia in both instances May 21. 

 These results abundantly confirm, and somewhat extend, the 

 work of last year.-* 



17. Uromyces Scirpi (Cast.) Burr. — Teliosporic material 

 on Scirpus Huviatilis (Torr.) A. Gray, sent by Rev. J. M. Bates 

 from Walbach, Neb., was sown May 22 on Cicuta maculata, giv- 

 ing abundance of pycnia May 31, and of aecia June 8. A sow- 

 ing made June i on Pastinaca sativa, the plants being especially 

 thriftv, gave no infection. On June 5 another sowing was made 

 on Oxypolis rigidus and Cicuta maculata, with no infection on 

 the former, but with fine showing of pycnia on the latter June 12, 

 and of aecia June 22. 



There is apparently no morphological difference between the 

 American rust and the corresponding European one, and the 

 hosts are also much alike. Sixteen years ago Dr. P. Dietel 

 showed by cultures-^ that in central Germany aecia are produced 

 on Siuni' I ati folium, which in habit and structure is much like 

 Cicuta maculata. He also found that, most curiously, aecia 

 could be grown from the same material on Hippurus vulgaris, 

 which belongs to another family of plants, showing that, in all 

 probability, the species is not closely circumscribed. 



Cultures made by Dr. Fr. Bubak in 1901 from Bohemian 

 material brought to light a biological form which only infected 

 Berula angustifolia.^^ 



In 1902 Dr. H. Klebahn attempted to repeat Dietel's cul- 

 tures, and found that teliosporic material from the same immedi- 

 ate region, the exact locality having been changed and the rust 

 destroyed, gave abundant aecia on Pastinaca sativa, but only 

 slightly infected Hippurus vulgaris, and infected Slum latifolium 

 and Glaux martima not at all.-'^ The year following he carried 

 out more extensive cultures. Teliosporic material raised from 

 aeciospores on Pastinaca sativa, infected both Pastinaca and 

 Berula angustifoUa. Teliosporic material from central Germany 



"* See Jour. Myc. 12 :19. 1906. 



"Hedwigia 29 -.149. 1890. 



" Centr. Bakt. 9' :926. 1902. 



"Jahrb. Hamb. Wiss. Anst. 20 -.33. 1903. 



