Cultures of Uredineae in 1916 and 1917 297 



relationships, transcending all deductions derivable from morpho- 

 logical study alone, must have remained unrecognized, or in so 

 far as dimly apprehended be wholly without demonstration. 



A number of correspondents assisted in securing needed ma- 

 terial for the season's work, and to them thanks are due. There 

 were available 170 collections with resting spores, and 9 with 

 active spores as in Aecidium and Gymno sporangium. Some 452 

 tests were made in a hanging drop to determine the germinating 

 condition of the spores. Only 69 collections of resting telio- 

 spores could be brought to germination from which 182 sowings 

 were made, and 17 infections secured. From the 9 collections 

 of fresh spores 12 sowings were made, and 3 infections secured. 

 The work was largely performed by Mr. C. C. Rees, a member 

 of the regular staff of the laboratory. 



Negative results in 1916. — Of the various attempted cul- 

 tures which failed to produce inoculations two are worthy of 

 record. 



1. Uromyces graminicola Burr, on Panicum virgatum L., 

 sent by Mr. E. Bartholomew from Stockton, Kans., was sown 

 April 25 on Euphorbia corollata, and again May 25 on the same 

 host, in both instances with no apparent result. In previous 

 seasons the same species was sown on a number of other hosts, 3 

 but in the meantime from morphological and distributional data 

 the conclusion had been reached that this form is probably cor- 

 related with Puccinia Pammelii on the same host, whose aecia 

 are known to be on Euphorbia corollata. Other attempts at cul- 

 tures should be made before abandoning the assumption. 



2. Puccinia on Carex Backii Boott (C. durifolia Bailey) ob- 

 tained by Mr. E. Bethel in February from near Denver, Colo., 

 was sown April 7 on Kibes Cynosbati, Boltonia aster oides and 

 Urtica gracilis, and again May 15 on the same hosts and on 

 Eleagnus argentea and Artemisia dracuncul oides. The same 

 form obtained by Mr. Bethel in March from Boulder, Colo., was 

 sown April 7, on R. Cynosbati, B. aster oides, and U. gracilis, 

 and April 15, on R. Cynosbati, U. gracilis, and E. argentea. 



3 See Jour. Myc. 12: 13. 1906; Mycol. 1: 232. 1909; 2: 220. 1910; 4: 12. 

 1912. 



