44 



Mycologia 



The next paper was by John A. Elliott on a new parasitic slime- 

 mold suitable for class work. This slime-mold causes a very- 

 serious disease of sweet potatoes. There are two methods of in- 

 fection, one by means of swarm spores and one by means of the 

 Plasmodium. Spots are caused by the plasmodium entering the 

 young rootlets. The plasmodium finally migrates from the 

 wounds, leaving pits. The paper was well illustrated by lantern 

 slides. Considerable discussion followed. 



Dr. Arthur again covered the main points in Mr. Rees's paper 

 on the Fritillaria rusts of Europe and America. From his studies 

 it was concluded that there were two species of rusts on Lillium 

 and Fritillaria hosts and that the American species were different 

 from the European. 



R. H. Colley spoke of the difficulty of diagnosing the white- 

 pine blister disease before the spores are developed. It has been 

 found by him that the pycnial scars are very characteristic and 

 with experience can be used in detecting the presence of the 

 disease. A number of slides were shown, illustrating the pycnial 

 scars and also the rusty color of the mature spores. 



The Uredinales of the West Indies were next treated by Dr. 

 Arthur. This study was taken up a year ago in connection with 

 extensive collections of F. L. Stevens, who for some time past has 

 been making a study of the parasitic fungi of Porto Rico. In 

 addition to these, Drs. Olive and Whetzel collected a number of 

 species not previously known. Other collectors have added to 

 the list, including Mr. Percy Wilson and other collectors from the 

 New York Botanical Garden. The total number of species known 

 from the West Indies is 214. It has been found that, so far as 

 the rust flora is concerned, the Cuban flora resembles that of 

 North America while the Porto Rican flora resembles that of 

 South America. One noteworthy fact in connection with the 

 West Indian rusts is the large number of short-cycled species. 

 It has been preciously supposed that short-cycled rusts were an 

 adaptation to a short growing season. Under tropical conditions, 

 twenty-five per cent, of the species are found to be short-cycled, 

 a fact which is directly contrary to previously accepted theories. 



Dr. Trelease presented the paper on the parasites of Meliola 

 in Porto Rico which was to have been read by Dr. F. L. Stevens. 



