Allen and Jolivette—Light Reactions of Pilobolus. 561 
meters, and to 12.4 centimeters below with the glass at 85 
centimeters. The results are given in detail in Table VII. 
Under “7-p ? is given' the number of sporanges that did not 
reach the vertical glass plate, but fell on a glass on the floor 
of the box. 
When plotted (Fig. 11), these data do not. give the modified 
parabolic curve of the path of a projectile, for the descent once 
begun is not rapid enough. The path of the individual spor- 
ange however is probably that of a projectile. 
0 _ 10 ao 30 40 SO 60 10 9° <?0 ,<7 ° 
s 
<0 
10 
T'ig 11 
Fig. 11. 
The Kesponse of Pilobolus When Subjected to Two Sim¬ 
ultaneous White Lights of Equal Intensity. 
A preliminary experiment was made to determine the general 
nature of the response of Pilobolus to two simultaneous light 
stimuli, using a box with two openings in one end. The box 
was of cardboard, light-proof, painted black' inside, and was 
42 centimeters long, 14 centimeters wide and 9 centimeters 
high. In one end were two circular holes 7.5 centimeters apart, 
each being 1.25 centimeters in diameter and 5.5 centimeters 
above the bottom. The glass was placed inside the box, against 
the end in which the openings were cut. 
The culture of Pilobolus , in a twG-inch flower-pot as before, 
was placed on its side with its surface vertical and facing the 
end of the box containing the openings. The center of the 
surface was on the level of the centers of the openings and was 
equally distant (32 centimeters) from each. The experiment 
was set up at night. Twenty-four hours later, a drawing was 
made, showing the distribution of the sporanges on the glass 
before the openings (Fig. 12). For purposes of comparison, 
a control experiment was set up exactly like the first except 
