166 BULLETIN OF THE BUREAU OF FISHERIES 
Table 7.— Effect of red liquor ( specific gravity 1.046) on the rate of feeding of Ostrea gigas (size, 
11.3X6.2 centimeters) . Salinity, 33.68 parts per thousand 
[October 16, 1929, Pacific Grove, Calif.] 
Time 
Temper- 
Concen- 
tration 
pH 
Rate of flow, cubic 
centimeters per hour 
Remarks 
ature 
parts per 
thousand 
Average 
Maxi- 
mum 
Mini- 
mum 
10.37 a. m.._ - 
° C. 
15.8 
0 
7.9 
3, 240 
3,240 
3,220 
2, 430 
11.07 a. m 
16.0 
. 2 
7.9 
3,026 
3,356 
11.40 a. m 
16.4 
. 4 
7. 9 
3, 143 
3,356 
3,130 
12.11 p. m 
16.8 
1.0 
7.3 
3, 156 
3, 356 
2,365 
3, 130 
12.35 p. m 
17.0 
2.0 
7.0 
1,944 
12.55 p. m 
17.0 
3.0 
6. 8 
1,730 
2,112 
2,365 
1, 470 
Current irregular. 
2.48 p . m 
17.4 
4.0 
6.7 
1,944 
Do. 
3.07 p. m 
17.4 
5.0 
6.4 
1 , 251 
1,944 
972 
Do. 
3.35 p. m 
17.6 
8.0 
6.0 
771 
1, 276 
583 
Do. 
3.52 p. m 
17.5 
10.0 
5.8 
1,244 
972 
Do. 
4.12 p. m 
17.5 
15.0 
5.7 
816 
1, 076 
609 
Do. 
Figure 41. — Effect of sulphite liquor on the rate of feeding of Ostrea gigas. Tem- 
perature, 15.8-17.5° C.; pH, 7. 9-5.7 
Since red liquor is an acid solution, its effect on the activity of the ciliary epithe- 
lium could be attributed to the increase in hydrogen-ion concentration rather than 
to the presence of certain toxic substances. If the inhibition of ciliary activity were 
due to the increase in the acidity of the water, it would be a simple matter to counter- 
act it by neutralizing the solution before it is discharged into the water. Unfortu- 
nately, this is not the case. In the experiment P13 (Table 6, fig. 40) the red liquor 
was neutralized by adding small amounts of NaOH until its pH was 7.1; various 
amounts of neutral liquor were added to the sea water, the pH of which was nearly 
constant (7.9 to 8.0), then the rate of flow of the water was measured. As can be 
seen from Table 6, neutral red liquor has a pronounced inhibitive effect on the rate 
of flow of water through the gills. 
