294 DopGE: STUDIES IN GENUS GYMNOSPORANGIUM 
GYMNOSPORANGINM JUVENESCENS 
The telial stage of G. juvenescens was obtained from Dr. J. J. 
Davis, Madison, Wisconsin, in April, 1916. Sori were present in 
the axils of the acerose leaves, but the witches’-broom effect was 
not pronounced. Three or four plants of Amelanchier intermedia 
and A. spicata that were in bloom at this time were inoculated. 
Infection was evident in five days. Aecidia matured in abundance 
on fruit and leaves as early as May I. 
Nine red cedars were inoculated in 1916. No infection ap- 
pears to have followed these inoculations; there are as yet, April, 
1918, no indications of swellings or the development of sori. 
GYMNOSPORANGIUM NIDUS-AVIS 
The red cedars on Long Island and in the vicinity of New 
York are badly infected with a Gymnosporangium which, if the 
infections are due to a single species, is certainly multiform in its 
manifestations. Amelanchier and Malus have been infected with 
spores taken from each of the following forms, although the inocu- 
lations were not made in each case with a single sorus: (1) Sori in 
the axils of densely crowded acerose leaves; (2) sori caulicolous, 
large branches forming coarse witches’-brooms; (3) trunk infec- 
tions, sori appearing in deep fissures in the thickened bark. There 
is perhaps another form recognized by the presence of long parallel 
cork ridges, about one centimeter in width, that mark the location 
of sori of former years. 
Several apple seedlings had been infected with spores from 
material resembling the second type mentioned above. A con- 
siderable number of aecidia matured. Spores from these aecidia 
were sowed on a red cedar, No. 418, in June, 1914. No infection 
was discovered on this cedar in 1915, but two sori developed on 
the main stem in May, 1916. In 1917, even on this small plant, 
the swollen sori coalesced in masses two inches long, The infec- 
tion has spread over five inches vertically during the past three 
years. Old and new branches growing from the infected portion 
of the stem appear not to be infected at all. It is a typical trunk 
. infection, and slightly erst: seen and Malus have 
been infected wit two years in succession 
and there can be no » dame that both the shad bush and the apple 
are host plants for this form of G. nidus-avis. 
