KUNKEL: ORANGE RUSTS OF RUBUS 561 
one case must an exception be noted. One spore was found which 
had put forth a long germ tube that branched into two parts. 
On one of these branches two quite normal sporidia were borne 
on typically formed sterigmata. It is difficult to explain this case. 
Either the spore which gave the promycelium was a con- 
tamination or the aecidiospores of Gymnoconia interstitialis are 
in rare instances capable of functioning as teleutospores. The 
writer is inclined to the latter view. 
In order to further test the germination of these aecidiospores 
a second sowing was made. This time the spores were dusted 
over the surface of three plates of tap water and three plates of 
Beyerinck agar. At the same time material of Caeoma nitens 
on Rubus frondosus Bigel. was brought into the laboratory from 
Van Cortlandt Park. These spores were also dusted over the 
surface of three plates containing tap water and three plates of 
Beyerinck agar. All of the cultures were made at the same time, 
on the same media and all were incubated at room temperature. 
A large percentage of the spores germinated in each of the cultures. 
The aecidiospores brought from New Hampshire produced long 
non-septate germ tubes that resemble in every way the germ tubes 
of other rust aecidiospores. Somewhat better germination was 
obtained on the agar than on the tap water, but the manner of 
germination was the same on the two media. The spores brought 
from Van Cortlandt Park gave practically one hundred per cent. 
germination and they produced in all cases promycelia. 
Having used up all of the aecidiospores brought from New 
Hampshire in germination and inoculation experiments a second 
trip was made to Glen on July 7. This time the Caeoma was 
collected from three different localities and on two species of 
Rubus, namely, Rubus canadensis L. and Rubus nigrobaccus Bailey. 
Many cultures were made from the aecidiospores obtained from 
the three different localities. In each case a high per cent. of the 
spores germinated and they all produced long non-septate germ 
tubes like those shown in Fics. 1 and 2. In order to study the 
nuclear behavior in the germ tubes a considerable quantity of 
germinating spores was fixed and stained according to a method 
outlined in an earlier paper (7). A study of the stained material 
shows that the long tubes typically contain two nuclei. These 
