Seed Carriage of Euphorbia Rusts 139 
In other cases the infection developed with the plant throughout the 
season, invading the new branches as they were formed. In general 
pyenia appeared first, followed shortly by aecia. Occasionally pyenia 
only appeared and in a few instances apparently only aecia developed. 
Aeciospores from the above material were sown on five uninfected 
plants and uredinia and telia of U. proéminens were produced upon 
the leaves and capsules. Later ten other plants became infected, show- 
ing uredinia and telia apparently from the aeciospores and uredinio- 
spores of infected plants. 
Uromyces dictosperma. 
Seed from plants of Euphorbia Arkansana heavily infested with 
telia of U. dictosperma was collected by Mr. E. Bartholomew at Stock- 
ton, Kansas, July 2, 1920, and sent to Dr. J. C. Arthur, who kindly 
turned the material over to me for this work. This seed was planted 
August 20, 1920, forty-two plants being obtained. These were trans- 
planted to a flat September 2d, and upon November 12th one plant 
showed infection, one branch being covered with aecia. This infected 
branch soon died and all the plants appeared free from rust until the 
last of March, when a number showed infection. The plant showing 
aecia in November again showed aecia upon one of its branches. Out 
of the forty-two plants, eleven showed infection, aecia or pyenia and 
aecia developing upon one or two branches. Later uredinia and telia 
appeared on most of the plants apparently from aeciospore infection. 
The branches infected with aecia soon died without setting seed and the 
plants finally showed only telia. 
Aeciospores from the above described material were sown on unin- 
fected plants and uredinia were produced. The urediniospores in these 
sori were, however, soon replaced by the characteristic teliospores of 
Uromyces dictosperma. From these cultures it is evident, therefore, 
that the more or less systemic aecia found on Euphorbia Arkansana 
associated with the teliospores of U. dictosperma represent the aecial 
stage of this rust. Aeciospores from these aecia give rise to uredinia, 
which, however, as such, exist for only a short time, the urediniospores 
being replaced by teliospores. Uromyces dictosperma in consequence is 
a full-cycled, autoecious species. 
It is considered that the above evidence is sufficient to prove that 
these two rusts are seed carried. The press of other work has not 
allowed the question to be investigated as to how this takes place. The 
investigations of Carleton would indicate that in the case of Uromyces 
proeminens the rust was carried on the surface of the seed since plants 
from seed treated with corrosive sublimate showed no infection. To 
explain the production of aecia, it would be necessary to assume, how- 
ever, that teliospores were carried on the seed and germinated while 
the plant was still young. In the above experiments the teliospores 
would have to germinate in the fall without overwintering, while in 
the field they would germinate in the spring after overwintering. Carle- 
ton was not able to obtain germination from the teliospores which were 
present on the seed at the time of planting. In consequence the manner 
in which this rust is seed carried will have to be left for future in- 
vestigations. 
