1914] JOLIVETTE—PILOBOLUS 93 
At 9:15 the tip seemed to have stopped bending and to have 
grown straight. The angle made with the light was 60°. From 
9:15 to g:50 the increase in length was slight, and the older portion 
of the curve seemed to have become slightly more bent. At 10:15 
the terminal sporangial swelling was well defined and the limits 
of the vesicular bulb could be discerned. The direction of the tip 
remained unaltered and formed an angle of 60° with the incident 
light rays (fig. 2). 
A group of , 
sporangiophores 
on the same cul- 
ture as the two de- 
scribed above and SS 
h 
subjected to the bs ¢ 
same stimulation 
from 7:15 P.M. until 9:55 were observed at 9:55. Three of them 
were still turned in the direction from which the afternoon light had 
come and away from the light used in the experiment. Apparently 
there was no response toward the light stimulus. In these three 
cases sporangium-formation had begun. The fourth sporangio- 
phore had been subjected to the same conditions. The tip was 
curved through 135° and proceeded to grow in the direction of the 
light. The tip was still 
slender and pointed. 
The difference in length 
between this one and 
the other three was 
noteworthy. It ex- 
Fic. 3 ceeded the other three 
by the length of the 
portion beyond the bend where it turned toward the light. The 
sketches of the four sporangiophores as they were at 9:55 are 
shown in fig. 3. _ 
At 8:15, May 19, 1910, an older culture was used. Sporangium- 
formation had started when the observations were begun. At the 
beginning of the experiment the five that were chosen for study 
were at different stages, the youngest showing the sporangium as a 
