1914] JOLIVETTE—PILOBOLUS 95 
At 7:27, January 20, 1911, the light was turned on a culture 
which had been exposed to the afternoon light, and observations 
were begun on five sporangiophores which were visible in one field. 
The first sporangiophore made an angle of about 80° with the direc- 
tion of the light. It was slender 
tipped. At 7:58 the tip showed a 
slight increase in length and this 
portion was very slightly curved 
toward the light. At 8:23 there 
was a slight increase in curvature t | 
toward the light. At 8:42 the tip 
had curved through 35°, making 
an angle of 45° with the light. At 8:50 the curvature had increased 
so that the angle between the direction of light and the tip was 
only 25°. At 9:30 the tip was pointed directly toward the light. 
From this time the tip grew directly toward the light (fig. 5). 
The second sporangio- 
phore observed was in 
much the same condition 
at the beginning of the 
experiment as the one just 
Pe. 4 described, except that it 
was about 1 mm. longer. 
The reaction in this case was first noticeable at 8:00 P.M., the 
curve being barely visible. The curvature then proceeded more 
rapidly, and at 8:35 appeared more strongly than in the others in 
the field. At this time it had passed through an angle of 30°. At 
8:42 the angle traversed 
was 45°. At 8:50 the 
angle made with the I \ } \ a o ay 
direction of the light 
rays was barely more Fic. 6 
than 10°, and at go:1 
the tip was directed straight toward the light and it continued in 
that direction until 9:50, when -the observations were concluded. 
The portion beyond the curve was then about three-fourths of 
the length below (fig. m 
Fie. 4 
