VOLUME LVII NUMBER 2 
THE 
BOTANICAL © able 
FEBRUARY ro14 
STUDIES ON THE REACTIONS OF PILOBOLUS TO 
LIGHT STIMULI 
Hatsy DM. Jorivette 
(WITH TWELVE FIGURES) 
The present investigation concerns itself for the most part 
with the problems of simultaneous stimulation. It was under- 
taken with a view to settling some of the problems suggested in a 
former paper on the light reactions of Pilobolus by Miss ALLEN 
and myself (1). Some of the objections inherent in the methods used 
in the earlier work were eliminated in the experiments here reported, 
and a study was also made of the reaction of single sporangiophores 
toward the light. 
The work was begun under Dr. R. A. HARPER at the University 
of Wisconsin and completed: under Dr. G. J. Petrce of Leland 
Stanford Junior University. I wish to acknowledge my indebted- 
ness for their criticisms and suggestions. I wish also to express my 
gratitude to Dr. D. H. CampseE t for his interest in my work and 
for his courtesy in extending all the privileges of his laboratory. I 
thank Miss RutH F. AtLEN, who began the study of the reactions 
of a single sporangiophore of Pilobolus toward the light and 
furnished the data taken on the evenings of May 18 and 109, 
IgIo. 
The present study of simultaneous stimulation by light is on 
the question of directive influence, and the literature discussed will 
concern that phase of light effect. The early work was carried 
on with light and gravity as the stimuli. Nott (4) in 1892 pub- 
: 89 
