1920] 
ZELLER—IMBIBITION BY WOOD AND SPORE GERMINATION 69 
and is exposed to the air from both sides. These devices were 
numbered, and after the chamber of the humidor, described 
elsewhere in this paper, had come to a constant humidity, one 
of them was lowered into the chamber through the opening in 
the top. By means of the lever it was hung on a wire without 
opening the chamber. In this way spores were exposed to the 
atmospheric conditions of the chamber without coming in 
contact with any other object. A new shaving was added 
to the chamber on 12 successive days. All were removed at 
one time, examined under the microscope, and the percentage 
of germination estimated on the basis of the total number of 
spores in a unit field. In table v the percentages of germination 
TABLE V 
RELATION à THE GERMINATION OF THE SPORES OF uae sele TO 
HE RELATIVE HUMIDITY OF THE ATMOSPHERE AT 25° C. 
Tet Per cent Per cent Toe Per cent Per cent 
Seay EE germination relative iere. germination | relative 
pee y (averages) humidity ||P YS/| (averages) | humidity 
10 — 1.5 63.0 5 76.0 96.5 
10 2.5 65.0 5 85.5 98.5 
10 3.5 67.4 5 100.0 99.0 
10 2.5 72.5 5 100.0 98.0 
7 4.0 78.5 5 95.0 98.0 
7 7.5 82.5 6 57.5 96.0 
7 5.5 85.5 6 80.0 98.0 
7 10.0 89.8 6 87.5 98.0 
5 20.5 90.5 6 92.0 99.0 
5 25.5 92.5 6 96.5 99.0 
5 70.0 95.5 6 100.0 98.5 
are the averages of three or four counts. In fig. 5 the relation of 
spore germination to relative humidity is presented graphically. 
This curve indicates that until the fibre-saturation point is 
reached the percentage of spore germination is very low, but as 
soon as the humidity of the air is sufficiently high to supply free 
