EFFECT OF CRUDE OIL POLLUTION ON OYSTERS 
185 
too - 
/so - 
140 
130 
120 
no 
100 
90 
80 
70 
CO 
50 
40 
I 
, 30 
^.20 
jk 
i 1 1 1 1 1 1 1 1 1 r 
Tlie average rates of flow of water, in drops per minute, were computed from 
the kymograph data. The time during which the record was taken varied for the 
period “Before treatment”, from 20 to 45 minutes; “During treatment”, from 15 
to 45 minutes; and “After treatment”, from 15 to 90 minutes. It is believed that 
these periods are of sufficient 
duration to eliminate the 
effects of accidental stimula- 
tion and other possible dis- 
turbances. 
Although both the win- 
ter and spring experiments 
show a depression in the rate 
of flow following treatment, 
the effect is much greater 
in the spring series. The 
average depression in rate 
of flow resulting from treat- 
ment for the winter series is 
18 percent. For the spring 
series it is 60 percent. This 
difference in the levels of 
depression for the two groups 
is presumably a function of 
temperature, and is due to 
the direct relationship exist- 
ing between temperature and 
rate of motion of the lateral 
gill cilia. It will be noted 
(table 12) that the average 
rate of flow before treatment 
in the winter series is 66 
drops per minute, while in 
the spring series the average 0 
is 130 drops per minute. 
The average temperature at 
the beginning of the experi- 
ments for the winter series 
is 14° C., while the spring 
average is 22° C. Thus an average increase of 8° C. in temperature approxi- 
mately doubles the rate of pumping while the depressing effect of the soluble 
fraction solution is trebled. 
Sol. fraction on 
Fxjot. 84 Control -• 
12 Sol. Fr. o 
79 Sol. Fr. o 
81 Sol. Fr. a 
_L 
_L 
5 15 25 85 45 
Time m m/nutes 
55 65 75 £>5 95 105 
Figure 9. — Effect of water soluble fraction of Lake Barre oil on the activity of the 
ciliated epithelium. Drop counting method. 
