Allen and Jolivette—Light Reactions of Rilobolus. 581 
percentages vary irregularly, it is noticeable that on the whole 
there is a gradual decrease in the proportion fired toward the 
blue and a proportionate increase in that fired toward the white 
as the culture is moved toward the latter. It appears then that 
the light of short wave length, as such, has no preponderating 
influence at least in determining the phototropic 1 reactions of 
Pilobolus. ' 
Whether the presence of two sources of light will affect the 
accuracy of aim of the sporangiophores can be ascertained from 
the results of the experiments just described by studying the 
number of sporanges which strike in the different areas of the 
respective targets. It would seem possible that if the pres¬ 
ence of one light influences the aim of the sporangiophores to¬ 
ward the other, some of the sporangiophores should be pulled 
out of the position of direct aim and nearer the vertical position. 
If, then, there be such an influence as that suggested, we shall 
except in these experiments to find a larger percentage of the spo¬ 
ranges above the center of the target than in the case in which 
only one light was used. 
We note, however, that the majority of the sporanges are al¬ 
ways below the center of the opening. On the blue glass there 
are 28% more below than above with the culture at four centi¬ 
meters distance, 19.3% more at 14 centimeters, 45.6% more at 
26 centimeters distance. In the case of the white light, also, 
the number below always exceeds that above the center of the 
opening. These results are given in complete form in Table 
XIII. The results make it seem probable that there is no in¬ 
crease in the number of sporanges landing above the opening 
due to the presence of a second source of light. 
A possible effect might also be shown in a, general tendency 
to inaccuracy of aim toward one light due to the presence of the 
other. The percentages of the total number of sporanges which 
land in area ] in the blue and white lights respectively, are, 
however, practically the same as in the case in which the two 
glasses were used separately (Compare Table XV with Table 
II). As before, there is a slightly larger proportion on area 1 
when the blue light is used than when the white light is used. 
