I0oo BOTANICAL GAZETTE [FEBRUARY 
Both of the pieces were painted a dull black. The surface of the 
culture was covered with black paper, exposing a circular area 2 cm. 
in diameter. This small area was selected in order to exclude 
objectionable features such as unevenness in surface of culture, 
irregularity of distribution, etc. The number of sporangia was 
thus somewhat limited, but the undesirable features above men- 
tioned were minimized. 
This set of experiments was carried on in a dark room at the 
University of Wisconsin during April, May, and June 1910, under 
the direction of Dr. R. A. Harper. 
As previously described, a new set of sporangia matures daily 
and is discharged in the forenoon or early afternoon. The records 
of the results of the experiments were made daily in the late after- 
‘noon or evening. A glass plate fitting inside the box and against 
the openings caught the sporangia as they were discharged toward 
one or the other of the two lights. 
The data were then recorded by means of a chart devioed to 
meet the requirements of the experiment. The chart consisted of a 
large white sheet of paper divided by means of parallel lines into 
vertical strips 1 cm. wide. This is the principle of the Wolfhiigel 
counter used by bacteriologists, and it was well adapted to the work 
and. The pieces of glass covering each of the 1-cm. openings 
fitted into the 1-cm. strips. In recording the data, the sporangia 
falling above and below the opening in the 1-cm. strip are recorded 
with those striking the opening. This is entirely fair, since, owing 
to the object of the experiments, we are concerned only with lateral 
distribution. Furthermore, our earlier experiments showed clearly 
the conditions of vertical distribution. The data for these experi- 
ments are recorded in table I 
In the first experiment 86 sporangia were discharged on the 
glass, 29 striking the vertical area containing the opening to the 
left and 25 that to the right. In the second experiment the total 
number was 60; 5 of these were on the area of the left opening and 
200n the right. In the third experiment 59 sporangia were counted 
on the glass, 5 and 18 being found on the left and right openings 
respectively. In the seventh all of the 22 sporangia discharged 
were fired toward the right opening, 10 of them striking the vertical 
