Allen and Jolivette—Light Reactions of Pilobolus. 539 
side could be determined. In order to count' the sporanges in 
each area, the glass on which the sporanges were caught was 
placed on a paper target with the areas marked off as noted 
above so that the part of the glass which stood opposite the 
opening coincided with the bull’s eye on the target. 
Only one experiment of this sort with an opening one centi¬ 
meter in diameter was made with white light. The number of 
sporanges discharged was 222. Of these, 90 (40.5%) struck 
the glass opposite the opening, within area, 1. 94 (42.3%) 
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Fig. 2. 
were found on area 2, 25 (11.2%) on area 3, 7 (3.1%) on area 
4, and 6 (2.7-%) on area 5. A curve plotted from these data 
is shown in Figure 2 (continuous line), using the percentages 
as ordinates and the areas as abscissas. 
It is seen that nearly eighty-three per cent of the total are 
found in areas 1 and 2, but of this number a few more are on 
area 2 than on area 1. It is to be remembered that area 1 is 
very small as compared with area 2, and also as compared with 
the size of the culture, which is five centimeters in diameter. 
On the whole, the data show that the sporangiophores are not 
able to aim with a great deal of accuracy at a one centimeter 
opening at 20 centimeters distance. Whether the results would 
be the same if the same number of single plants were each placed 
