WHITE-PINE BLISTER RUST. 31 
GERMINATION OF THE PYCNOSPORES. 
Plowright states that pycnospores (spermatia) of some of the 
Uredinales have been germinated in sugar solutions by Cornu and 
himself (110). Brefeld (7) states that the spermatia of several rusts 
have been germinated in culture solutions. Later Carleton (10) 
stated that he had been able to germinate the pycnospores (sperma- 
tia) in but a single instance. 
The spermatia of TJredo caeoma-nitens Schwein., budded sparingly on May 31, 1893, 
after 24 hours in a dilute solution of honey, but would not germinate in water. 
Still later he said (11): 
Until recent years it was not supposed that the spermatia produced regular germ 
tubes, but that the germination is always simply a process of budding. Dr. N. A. 
Cobb and the writer have shown, however, that ordinary germ tubes are produced in 
the germination of these spores as well as in the other spore forms * * *,. Spermatia, 
though germinating readily in water, will be found to do much better in a rather 
dilute sugar solution, or perhaps still better in a solution of honey. 
Investigations were made in 1918 by York and Overholts, 12 who 
tested their germination in water and in various solutions of glucose, 
cane sugar, dextrose, maltose, lactose, peptone, extract of macerated 
Ribes leaves, and extract of macerated pine bark. Fresh pycnospores 
gave no germination. Pycnospores subjected to the cold of an ordi- 
nary refrigerator from 3 to 20 days gave degrees of germination 
increasing with the length of time in cold up to 18 days. Germina- 
tion occurred in 3, 5, and 6 per cent cane sugar and in 3, 6, and 10 
per cent dextrose. The stronger dextrose solutions gave the best 
results. No germination occurred in tap water in any case. 
SEASON OF PRODUCTION OF PYCNIAL SPOTS, DROPS, AND SCARS. 
The dark spots (PL II, fig. 2, b) which precede the exudation of the 
pycnial drops may be found in the infected bark at all times of the 
year. Records and observations made from 1909 to date furnish 
definite data on the season of pycnial drop formation. (See Table V, 
p. 72.) The pycnial drops are produced immediately after the 
racial season; that is, from about June 20 until winter. The rusty- 
brown scars left after the disappearance of the drops may be seen 
at all times of the year on old cankers. On new infections the scars, 
of course, do not appear until the drops have formed and disappeared. 
All of these are positive symptoms of this disease in white pines. 
THE ^ECIA AND ^ECIOSPORES OF CRONARTIUM RIBICOLA. 
SEASON OF PRODUCTION OF THE JECIA. 
The secia develop at varying dates in the same locality in different 
years, according to the season. The locality, whether a warm or 
cold exposure, at a low elevation or a high one, well to the south or 
J - York, H. H., and Overholts, L. 0. The germination of the pycnospores of Cronartium ribicola. Seen 
in manuscript. To be published in Phytopathology. 
