i8o 
GILBERT MORGAN SMITH 
amount of sunshine being very near the maximum for this time of the 
year. The local office of the Weather Bureau records the total energy 
of the sun's rays in the form of calories per minute per square centi- 
meter of surface. The curves for the two days are almost identical, 
so that no distinction can be made between the two on the basis of 
different Hght intensities. Table II gives the light intensities at the 
times that the samples were collected on the 7th of July. 
Table II 
Weather Conditions at the Time Samples Were Collected 
Velocity of Wind 
Total Sunshine (Morning July 7) 
Date 
Av. Vel. in Miles 
per Hour 
Max. Vel. 
Hour 
Cal. per Min. 
per Sq. Cm. 
July 6 
July 7 
4-2 
8 
8 
4:25 
5:30 
6:30 
7:30 
8:30 
10:00 
12:00 
0.00 
0.12 
0.39 
0.60 
0.82 
1.07 
1.28 
Table I shows that the clearly defined stratum found on the morn- 
ing of the 6th was still at a depth of three meters at sunset, when the 
sun's rays are less intense than in the morning. After sunset, however, 
the band was broken up, a majority of the colonies sinking from one to 
three meters. At sunrise on the following morning the colonies were 
in the upper three meters and as the day progressed they migrated 
toward the surface until at noon over ninety percent were in the upper 
meter. The data on this gradual rise vary somewhat from hour to 
hour, but these variations are, in my opinion, due to experimental 
errors and do not represent changes in the position of maximal dis- 
tribution. 
Table III 
Table Showing Temperature Range for the Upper Seven Meters of the Lake 
Depth in Meters 
0 
I 
2 
3 
4 
5 
6 
7 
25.0 
24.4 
24.0 
23.1 
22.3 
21.4 
20.5 
19.2 
It is well known that Volvox responds to various stimuli. Changes 
in temperature, chemical composition of the water, direction of the 
