DODGE: STUDIES IN THE GENUS GYMNOSPORANGIUM § 133 
small plant which I was able to transplant and grow in the greenhouse. 
In 1915 this small burl bore two sori. The same burl bore six sori in 
1916. The branch was six years old when cut. The mycelium spreads 
quite evenly through the cortex and is especially abundant beneath a 
sorus where we find one or two large haustoria in nearly every cortex 
cell. The medullary ray cells of the cortex are likewise attacked and 
the mycelium penetrates down to the cambium. The walls of the 
tracheids are somewhat thicker than usual, in this respect differing 
from the specimens examined by Wornle. 
I have been unable to find any intracellular hyphae, and in this 
six-year-old branch there are certainly no hyphae inside of the cambium 
ring, that is, in the wood cylinder, such as Harshberger describes. 
The most striking feature about this fungus is the great abundance 
of large haustoria found in nearly every cell of the cortex in the 
vicinity of a sorus. 
GYMNOSPORANGIUM CLAVIPES 
The red cedar may be infected with G. clavipes without difficulty 
by spraying with aecidiospores. Plowright® states that it takes two 
years for G. clavariaeforme to mature sori, but Tubeuf*® found that 
sori developed one year after inoculation of the juniper. My experi- 
ence with G. clavipes may serve to explain this discrepancy. 
On August I, 1915, a small cedar was inoculated with Gymno- 
sporangium clavipes. A few sori appeared in 1916 on what was, in 
1915, the growing region of the main stem. In 1917 sori burst out 
quite generally over the plant. ‘The question has arisen: Is it possible 
that from the original point of infection of 1915 the mycelium ran 
down the main stem out into the branches where further sori formed 
in 1917? Inspection showed that the sori were not evenly scattered 
along the branches, but appeared in groups with intervening spaces 
of some length between, varying from one to several cm. Serial 
sections of some of the smaller branches made at points between 
groups of sori do not show the presence of mycelium. For several 
inches near the top of the main stem the sori are so close together 
that mycelium appears to be continuous. It is noteworthy, however, 
that there are no sori on those parts of the plant that have grown 
since the plant was inoculated in August, 1915. The mycelium is 
intercellular and lies for the most part well out in the cortex just 
beneath the cork, some hyphal ends even pushing in between the inner 
cork cells. It may require only one year for full development at the 
5 Plowright, C. B. British Uredineae and Ustilagineae. 1893. 
6 Tubeuf, C. Mitteilungen iiber einige Pflanzenkrankheiten. Zeitschr. 
Pflanzenkr. 3: 201-205. 1893. 
