EFFECTS OF PULP MILL POLLUTION ON OYSTERS 
163 
This study was carried out in October, 1929, at the Jaques Loeb Laboratory at 
the Hopkins Marine Station, Pacific Grove, Calif. Oysters for experimental work 
were received from Olympia ( Ostrea lurida ) and from Samish Bay ( 0 . gigas, the 
Japanese oyster). Olympia oysters, shipped by boat from Olympia to San Francisco 
and by train from San Francisco to Pacific Grove, arrived on the fifth day; Japanese 
oysters were expressed and were en route four days. In both cases the oysters arrived 
in good condition and apparently did not suffer from transportation. They were 
placed in large tanks with running sea water where they were kept for four weeks. 
There was no indication of unusual mortality among the oysters. The temperature 
of the water in the tanks (recorded three times a day) fluctuated from 15° to 17.5° 
C.; its salinity (daily observations) varied from 33.40 to 33.84 parts per thousand. 
The method employed in the present investigation consisted in measuring the 
velocity of the current of water in the circular glass tubing introduced into the gill 
cavity. Since this method was fully discussed in previous papers by the author 
(Science, 1926, Vol. LXIII, pp. 233-234; Journal of General Physiology, 1928, Vol. 
XI, pp. 415-431; Bulletin of the Bureau of Fisheries, 1928, Vol. XLIV, pp. 1-39) a 
description of it here is omitted. Because of the small size of the Olympia oyster, 
the glass tubing used in the experiments with this species was of smaller diameter 
than the tubing used in the experiments with Japanese and Eastern oysters. During 
the experiments, oysters were kept in enamel trays containing 5 liters (Olympia 
oyster) and 10 liters (Japanese oyster) of water. The water was continuously stirred 
and aerated. No attempts were made to keep the temperature constant; it fluctu- 
ated within 2° C. "Red liquor” was received from the Shelton pulp mill; its spe- 
cific gravity at 15.6° C. was 1.046. Various amounts of red liquor were added to the 
water in which the oysters were kept, and the rate of flow of water was measured 
after the oysters were allowed to remain for at least 15 minutes in a given concen- 
tration. Each experiment lasted several hours, depending on the number of observa- 
tions. The values of the rate of flow given in figures are the means of 10 or 20 
measurements. The limits of fluctuation are shown in the tables. Numerous con- 
trols show that under the conditions of the experiments, the rate of flow through the 
gills of an oyster, which was kept in pure sea water for several hours remained con- 
stant. Thus the decrease in the rate of flow of water observed during the present 
investigation can be attributed to the effect of the red liquor. 
The results of the experiments are shown in Tables 5-7 and in Figures 39-41. 
For computing the rate of flow in cubic centimeters per hour, the following for- 
mula was used : 
V=450t rD 2 S 
where D is the diameter of the glass tubing in centimeters and S is the velocity 
of current at the axis in cms/sec. In the case of Ostrea lurida, the diameter of the 
glass tubing D was 0.33 centimeter; in the case of the Japanese oyster, D equaled 
0.68 centimeter. 
An examination of the results of the experiments (Tables 5 and 6, figs. 39 and 
40) shows that the addition of 2 parts per thousand of red liquor causes a decrease 
in the rate of flow of water through the gills. At the concentration of 6 parts per 
thousand, the flow of water in Ostrea lurida is about one-fifth of its normal rate; at 
9 parts per thousand, it constitutes only 7.3 per cent of the normal rate of a given 
specimen. It is interesting to note that, beginning with the concentration of 4 parts 
per thousand, the current becomes less regular, the irregularity increasing with the 
increase in concentration. 
