Arthur: Cultures of Uredineae in 191 i 53 



hosts, a possibility barely touched by the present attempt at 

 culture. 



2. PucciNiA ScHEDONNARDi K. & S., ou S chedofinardus panic- 

 tilatus (Nutt.) Trel, collected at Stockton, Kans., by Mr. E. Bar- 

 tholomew, was sown April 19, on Aesciiliis glabra, Xanthoxylum 

 americanum, Hydrophyllum capitatum, Sidalcea oregana, Callir- 

 rJioe involucrata, and Onagra pallida, with no infection. Similar 

 material in former years was sown on twenty-eight other species 

 of hosts. ^ 



3. Gymnoconia interstitialis (Schl.) Lagerh. No attempts 

 have been made, so far as the writer knows, to propagate any 

 species of rust by means of its pycniospores, except one made by 

 Dr. Frank D. Kern in 1910, and not heretofore reported. He 

 sowed pycniospores from Amelanchier ere eta, belonging to Gym- 

 nosporangiuni clavariaeforme, upon young leaves of A. ereeta by 

 pricking and otherwise mutilating the epidermis, but without re- 

 sults. It is well known that the growth of such spores soon 

 ceases in a liquid culture the same as with any other rust spores, 

 only sooner, as they are much smaller and contain less nutriment. 

 But it has not been shown that they will not form a mycelium 

 when suitably placed upon or within the tissues of a host plant. 

 The prominent and abundant pycnia of the blackberry rust, 

 which mature in advance of the aecia, seem especially favorable 

 for such a trial. Pycniospores from Rubus allegheniensis taken 

 when perfectly fresh were sown May 9 on young leaves of two 

 different plants of the same species, which were well established 

 in pots. The spores were not only placed on the surface of the 

 partly grown leaves, but were also pricked into the tissues in 

 places with a needle. This was done to imitate the probable dis- 

 persion of such spores by insects, for which the nectar secreted 

 by the sori may have an attraction. No infection was obtained. 

 Neither in this attempted culture nor in that by Dr. Kern was 

 any examination made to ascertain what growth the pycniospores 

 may have made. 



Successful cultures supplementing previous work. — The 

 facts derived by growing the following species of rusts supple- 



^ See Bot. Gaz. 35: 11. 1903; Jour. Myc. 13: 193. 1907; 14: n. 1908; Mycol. 

 I : 231. 1909 ; and 4 : 10. 1912. 



