EFFECT OF CRUDE OIL POLLUTION ON OYSTERS 
169 
Table 8 — Average number of hours oysters remain open — Continued 
IN RUNNING SEA WATER 
Oyster no. 
Dates 
Days 
Hours 
Temper- 
ature 
range 
Oyster no. 
Dates 
Days 
Hours 
Temper- 
ature 
range 
1931 
° C. 
1931 
° C. 
119 
Julv 19-27 .. 
8 
11. 2 
28-30 
84 
Sept. 2-10 
5 
10. 0 
22-25 
Do . 
8 
12.4 
27-30 
Do 
Sept. 10-21 
7 
9.0 
23-26 
Do 
8 
9.0 
27-30 
Do 
Sept. 21-29 
6 
7.0 
22-25 
Do 
8 
9. 1 
27-30 
121 
Sept. 2-10.. 
8 
12.0 
22-25 
Do.... 
6 
6. 2 
27-30 
Do __ 
Sept. 10—18 _ 
8 
11.5 
23-26 
Do.. . 
7 
7.0 
28-30 
Do 
Sept. 19-27.. 
8 
10.0 
22-25 
Do ... 
4 
7.0 
22-25 
311 
Sept. 2-10 
8 
10.0 
22-25 
Sept. 9-18 
8 
6.0 
22-25 
Do 
Sept. 10-18 
8 
6.4 
23-26 
Do 
Sept. 18-26 
8 
6.0 
22-25 
Do 
Sept. 19-27 
8 
6.0 
22-25 
170 
May 31-Juno 5 
s 
14.0 
22-2.5 
Do 
June 5-13 
8 
10.4 
24-27 
1932 
Do.... 
9 
11. 1 
24-27 
68 
July 25-Aug. 1 
8 
12.0 
27-30 
Do... 
5 
9. 2 
26-29 
Do 
Aug. 1-9 
8 
12.4 
27-30 
Do . . 
6 
9.0 
27-30 
Do 
Aug. 9-17 
8 
12. 1 
27-30 
Do 
6 
12. 1 
28-30 
Do 
Aug. 17-25 
8 
9.0 
28-30 
P 
Aug. 21-25 
4 
10. 7 
24-27 
121 
June 20-27 
7 
8.3 
25-28 
R 
4 
11.9 
24-27 
Do 
7 
9.3 
27-30 
84 . 
July 19-27 
8 
8.5 
28-30 
Do 
July 4-10 
6 
11. 7 
28-30 
Do . 
8 
13.0 
27-30 
124 
June 25-July 2 
7 
15. 0 
27-30 
Do . 
8 
14. 0 
27-30 
Do.... 
July 2-10...’ 
8 
14.3 
28-30 
Bn 
\ np 19 19 
7 
10 0 
9.7 30 
Do 
Aug. 19-2G 
7 
10.0 
27-30 
10. 
292 
i 9. 6 
22-30 
Do. 
Aug. 26-Sept. 2 
7 
10.4 
28-30 
1 Average. 
The behavior of the oysters left in running water under oil was compared with 
that of the specimens kept in clear sea water under the same conditions — mounting, 
attachments to recording apparatus, volume of dishes, rate of flow of water, and 
temperature. 
In view of the finding by Hopkins (1931) that temperature is one of the factors 
determining the length of time during which oysters remain open, the comparison 
between normal and experimental oysters was made for the same ranges of tem- 
perature. In presenting the results of the experiments (table 8) the average number 
of hours of activity of oysters during June, July, August, and September of 1931 and 
1932 was compared with the activity of oysters left under oil in July and September 
1933. By examining table 8 one can detect no significant difference in muscle 
behavior of the two groups of oysters. The number of hours of activity per day 
varied between 8.9 and 12.2 in the oysters kept under oil and between 8.8 and 11 
in the untreated oysters. No significant differences are apparent in the average of 
292 days of untreated oysters compared with the averages of 292 days of casters 
kept under oil. The average numbers of hours of activity per day for the whole 
range of temperature 22°-30° C. were 9.6 hours for the untreated and 10.5 hours for 
the experimental oysters. 
The question may arise that the difference in the muscular activity of oysters 
kept under oil and under normal laboratory conditions was unnoticeable because of the 
wide temperature fluctuations during the experiment. That this is not the fact can 
be seen from table 9 in which the average number of hours the oysters were open are 
computed for various temperature ranges. On account of daily temperature fluctua- 
tions in the laboratory water supply it was necessary to group the results of the 
observations into six overlapping classes. The results indicate very clearly that 
under the conditions of the experiments oil had no effect on the number of hours 
the oysters were open. 
