( 
EXPULSION OF ASCOSPORES 503 
of the spores, since an evident wind is not necessary to scatter the 
spores, but only helps to secure a wider dissemination. 
Method 
A study of various phases of ascospore expulsion under artificial 
conditions has been carried out during the past year. A series of 
nine main experiments covering practically the entire year of 191 3 
was conducted. Specimens of excellent quality showing mature 
perithecial stromata were obtained at Emilie, Bucks County, Pa., 
and fresh material was always collected for each test. Great care 
was taken not to let the specimens dry out previous to starting the 
experiments. 
In conducting the tests, small pieces of bark of approximately 
3-5 X 1.5 inches were placed on two layers of blotting-paper in shallow 
granite trays, 8 X 12 inches. Six pieces of bark were usually used 
for each tray and in selecting the specimens care was taken to secure 
pieces with a uniform distribution of perithecial stromata. Control 
specimens were always used and whenever possible they were taken 
from the other half of pieces used for the test. If this was not possible 
pieces of bark of uniform character were selected. Slides were sup- 
ported and fastened over the bark by the following method: Two 
pieces of match sticks of the same length as the width of the slides, 
were dipped in melted wax (beeswax and resin) and one placed across 
each end of a slide. The wax was allowed to harden and the sticks 
were held securely. When placed on the bark the slides were sup- 
ported about 2-3 mm. above the perithecial necks and thus sufficiently 
near to catch the ascospores on their under surfaces whenever expulsion 
occurred. In order to support the slides over the same material each 
day, four to six pins were stuck into the bark at the sides and ends 
of the slides. Each time before moistening the specimens the slides 
were removed and water of the same temperature as the room or 
incubator chamber was sprayed on the surface of the specimens and 
the blotting paper was also thoroughly drenched. Records were taken 
once a day, that is, the individual spots, each of which represents 
an active ostiole, were counted and their density noted. Not less 
than twelve specimens were used for each experiment, except in one 
or two cases with minor tests, and a like number was used for the con- 
trol. Complete temperature records were obtained for each experi- 
ment by the use of Friez thermographs. 
