184 
BULLETIN OP THE BUREAU OF FISHERIES 
Table 13. — The effect of soluble fraction of Lake Barre oil on the rate of pumping of water by the gills 
of the oyster 
[Beaufort, 1934, spring experiments] 
Experiment 
no. 
Date 
Average number 
drops per minute 
Effect 
of 
treat- 
ment 
Dura- 
tion of 
test in 
min- 
utes 
Specific gravity, 
17.5/17.5° C 
Increase 
in 
specific 
gravity 
of 
soluble 
fraction 
Tempera- 
ture, ° O. 
Number 
of wash- 
ings 
Recovery 
time 
Before 
treat- 
ment 
Dur- 
ing 
treat- 
ment 
After 
treat- 
ment 
Labora- 
tory 
sea 
water 
Soluble 
frac- 
tion 
Be- 
gin- 
ning 
End 
Per- 
cent 
Min- 
utes 
CONTROLS 
Percent 
73 
May 9 
44 
40 
38 
91 
78 
1.0234 
21. 7 
22.0 
74 
121 
128 
134 
106 
71 
1. 0237 
21. 6 
21.5 
84 
May 16 
139 
141 
137 
101 
92 
1. 0242 
20.9 
21.15 
86 
115 
114 
115 
99 
55 
1.0242 
21. 3 
21. 45 
SOLUBLE 
FRACTION 
71 
May 7 
109 
49 
73 
45.0 
5 
1. 0223 
1.0177 
0. 0007 
21. 5 
21. 5 
1 
72 
35 
72. 
May 9 
128 
71 
119 
55.0 
4 
1. 0234 
1. 0177 
.0007 
20.9 
20.9 
1 
87 
30 
75 
May 10 
132 
69 
64 
52.0 
9 
1. 0237 
1. 0177 
.0007 
21. 6 
21.7 
1 
42 
10 
76 
__ do 
124 
98 
122 
79.0 
10 
1.0237 
1.0122 
.0115 
21. 7 
21.9 
92.3 
20 
77 
__ do 
129 
85 
99 
66.0 
8 
1. 0237 
1. 0244 
.0007 
21.9 
22. 1 
1 
62.9 
10 
78 
May 14 
141 
13 
129 
9. 2 
8 
1. 0242 
1. 0247 
.0008 
22. 1 
22. 4 
1 
96 
30 
79 
__ do 
136 
19 
106 
14.0 
8 
1. 0242 
1. 0249 
.0007 
22.4 
22.7 
2.. 
102 
30 
80 
146 
27 
105 
18.5 
8 
1. 0242 
1. 0247 
.0005 
23.3 
23. 3 
3 
75 
30 
81 
156 
94 
132 
60.3 
8 
1. 0242 
1. 0250 
.0008 
22.9 
22.5 
3 
87.9 
20 
82 
___do 
133 
85 
119 
64. 0 
8 
1. 0242 
1. 0246 
.0004 
22.5 
22.4 
4 
91 
15 
83 
126 
33 
100 
26.2 
20 
1. 0242 
1. 0245 
.0003 
22.3 
22.6 
93 
10 
85 
May 16 
133 
31 
107 
23.3 
23 
1. 0242 
1. 0244 
.0002 
21. 1 
21.3 
5 and 6_. 
79. 1 
20 
87 
May 17 
87 
27 
55 
31.0 
24 
1. 0241 
1. 0243 
.0001 
19.1 
19. 1 
6 and 7.. 
64. 1 
30 
88 
May 21 
154 
42 
103 
27.3 
38 
1. 0212 
1. 0245 
.0005 
24.2 
24.3 
8 and 9_. 
70 
20 
89 — . 
May 22 
126 
38 
93.5 
30.2 
12 
1. 0230 
1. 0237 
.0007 
24.8 
24.8 
9 and 10. 
68 
15 
Average 
130. 6 
52.0 
101. 6 
40. 0 
22. 1 
78.7 
21.6 
Note.— A verages do not include controls or experiment no. 76, winch was made with dilute sea water. 
The column in table 13, marked “Number of washings” refers to the number 
of times the same oil has been stirred with sea water. In the winter experiments, the 
oil was used only once, then discarded. In the spring experiments as many as 10 
extractions were obtained from a single sample of oil without exhausting its toxicity. 
One must bear in mind that because the oysters in these experiments are kept 
in running water, which is gradually replaced by the solution, the duration of each 
test lasted only a short period of time, varying from 4 to 38 minutes, depending on 
the amount of solution available. In figure 9, representing the results of three experi- 
ments, the time when the treatment began is marked with a vertical line. It has 
been estimated that the sea water in the experimental chamber (fig. 5, Ch) was com- 
pletely replaced in 12 minutes, and that the same period of time was required to 
replace the oil extract with normal sea water, but there was no means of checking 
the exact concentration of solution in the chamber at the beginning and end of the 
test. 
A decrease in the rate of pumping of water, caused by the oil extract, is notice- 
able almost immediately upon the beginning of treatment, and continues as long as 
the toxic substances are present in the water. There was a wide difference in the 
sensitivity of various oysters. While in some of them the pumping was completely 
inhibited, in others it was only slightly depressed (table 14). 
