296 DopGE: STUDIES IN GENUS GYMNOSPORANGIUM 
(six inches high June 6, 1915) was inoculated June 21, 1916. 
On March 22, 1917, twenty-one days after it had been taken from 
the cold frame, one very light-colored orange-yellow sorus de- 
veloped in the axil of the leaf. This was supposed to be a sorus of 
G. clavipes that resulted from accidental infection in 1917. The 
little branch was marked with a tag. The plant was taken from ~ 
the cold frame again January 7, 1918. On February 15, there 
were two light-colored sori in the axils of the leaves of the tagged 
branch. February 19 two more sori were discovered in the axils 
of leaves of another branch, and two strictly foliicolous sori on 
opposite leaves of another branch. March 5 another foliicolous 
sorus appeared on another branch, and at the base of a larger 
branch a small brown sorus was found, upon removing a piece of 
loose cork. All of the leaf sori were very light colored and looked 
like G. clavipes. The mycelium has been traced from the infected 
leaves down into the branches for about two centimeters. The 
infected branches are all on parts of the plant that have grown 
since it could have been exposed to natural infection. I have 
proved by the examination of spores, by sections of infected leaves 
and branches and by infection of the shad bush that this cedar 
was infected in 1916 with G. nidus-avis. Some of the infections 
appeared one year after inoculation, while it undoubtedly re- 
- quired two*yearsefer other sori to mature. This is the fourth 
species of Gymnosporangium which I have found requiring either 
one or two years in which to mature the teleutospores. Under 
favorable conditions the rust may develop in one year. 
GYMNOSPORANGIUM TRANSFORMANS AND G. FRATERNUM 
Kern (8) describes G. fraternum as an annual species. The 
writer (3) called attention to the fact that there are two leaf forms 
of this genus on Chamaecyparis, both of which are frequently 
perennial, and in another paper (4) showed how the two forms 
could be distinguished by the character of the buffer cells that 
precede the teleutospores in the sori of each. 
Blueprints were made of infected branches so that leaves 
bearing sori could be located on the prints. In many cases it was 
found that sori developed a second and third year on the same 
leaves. 
