GERMINATION OF AECIOSPORES, UREDINIOSPORES, 
AND TELIOSPORES OF PUCCINIA CORONATA? 
G. R. HOERNER 
During comparatively recent years several workers have con- 
tributed considerable information concerning the phenomena of 
spore germination of crown rust of oats. The data herein recorded 
were the result of a series of experiments undertaken to determine: 
(1) the viability of aeciospores collected in several localities on 
species of Rhamnus; (2) the length of time urediniospores from a 
number of grass hosts, obtained in different localities, would remain 
viable; (3) the conditions under which urediniospores developed 
from artificial inoculations of oats in the greenhouse could retain 
their ability to germinate; (4) the optimum temperature for the 
germination of viable urediniospores; (5) whether teliospores devel- 
oped on oat seedlings in the greenhouse would germinate imme- 
diately; and (6) how early in the spring teliospores produced in the 
field on a variety of hosts and collected in various places would 
germinate. 
AECIOSPORE GERMINATION.2—From June 22 to July 11 inclu- 
sive specimens of rusted Rhamnus were collected at Montevideo 
and Moorehead, Minnesota; Wahpeton, North Dakota; Aberdeen 
and Brookings, South Dakota; and Beaver Dam, Wisconsin. 
Immediately following collection in the field, the fresh material was 
posted to Saint Paul, Minnesota, where the specimens were uni- 
formly packeted in manila envelopes and filed in tin herbarium 
case boxes. The minimum period from the date of collection to 
the time the spore germination tests were made was 167 days. 
Negative results were attendant upon all attempts at germination 
of the aeciospores from any of the specimens. 
‘Investigations carried on while a graduate student at the University of 
Minnesota, 1916-1918. 
? All spore Dee tests in these experiments, unless otherwise stated, were 
made in hanging drops of distilled water in van Tieghem cells at room temperature 
(about 18°C.) 
173] ‘ {Botanical Gazette, vol. 72 
