540 Wisconsin Academy of Sciences, Arts, and Letters. 
opposite the center of the opening is of course not shown by 
this experiment. 
In the next experiment, the light was admitted through an 
opening four centimeters in diameter, the culture still being 
kept at 20 centimeters distance. The target (Fig. 3) consisted 
of three concentric circles one centimeter apart. The inner 
circle was two centimeters in diameter. Consequently, areas 
1 and 2 are both within the illuminated area. The size of the 
inner circle was chosen with the possibility in mind that the 
sporanges might be fired toward the center of the illuminated 
area. The areas were numbered from within outward as be¬ 
fore, area 4 being all the space outside the third circle. 
Pig - . 3. Target consisting of three concentric circles 01 cm apart The inner 
circle is 2 cm. in diameter. Line A B is a horizontal line drawn through the 
center of the circles. 
In this experiment the total number of sporanges discharged 
Was 03. 07 (72 %) of this number were found on area 1; 
21 (22.5%) on area 2 ; 2 (2.1%) on area 3; and 3 (3.2%) 
on area 4. The curve plotted as in the foregoing experiment is 
shown in Figure 4 (continuous line). 94% of all the spor¬ 
anges landed within the area covered by the four centimeter 
opening—-more than twice the proportion that landed within 
the area of the smaller opening in the preceding experiment. 
The next series of experiments was intended to test the suc¬ 
cess of the sporanges in striking an illuminated area when the 
culture is removed to successively greater and greater distances 
in a horizontal direction. The object was to show whether the 
organism compensates for the effect of gravity on the path of 
the sporange by aiming high at a more distant source. The 
lower edge of the culture was kept on a level with the lower 
edge of the opening. Since the surface of the culture was five 
