EFFECTS OF PULP MILL POLLUTION ON OYSTERS 
129 
is probable that the sensitivity of oysters to foreign substances may be decidedly 
different from that of fishes. 
The problem of the effect of factory wastes on the aquatic life in streams is very 
different from the problem which grows out of the dumping of such wastes into 
bays and estuaries where oysters occur. While the flowing water of a stream con- 
stantly carries away fluid wastes, the more sluggish waters of a tidal basin are liable 
to absorb such substances and retain them. In the latter case, the tidal currents 
do not readily eliminate pollution. In a body of water of this kind, oysters would 
be subjected to the foreign substance more continuously and for longer periods of time. 
Sulphite liquor contains a large quantity of calcium sulphate in solution. When 
the liquor is neutralized with sodium hydroxide this appears as a precipitate, rela- 
tively insoluble in neutral fresh water but quite soluble in sea water. That the 
calcium sulphate may be partly responsible for the toxicity of the liquor is suggested 
by the observations of Oku, Ito, and Fujita (1901). They found that Japanese 
oysters died in aerated solutions of calcium sulphate in sea water in concentrations 
of 0.633 grams per liter and above. The lowest concentration which would produce 
death was not determined. Oysters 2 and 3 years old were found to be more sus- 
ceptible than 1-year-old specimens. In a later publication by Oku (1904), it was 
stated that oysters died as a result of the presence of calcium sulphate only in rela- 
tively warm water, for no deaths occurred in a similar series of tests made in winter. 
A further statement in this publication was to the effect that meats of oysters in 
ordinary sea water contained less copper than those kept for some time in solutions 
of calcium sulphate in sea water. This is an interesting suggestion but further 
evidence would be required to demonstrate the significance of the observation. 
MATERIAL AND METHODS 
For the experimental work Olympia oysters ( Ostrea lurida ) were taken fresh from 
the dikes of the Blass Oyster Co. in Oyster Bay. These specimens were selected 
because of their excellent condition, showing that they were relatively normal oysters 
and not obviously suffering from any cause as is the case with Oakland Bay oysters. 
The oysters used were all of approximately the same size, about 4.5 to 5.5 centimeters 
long by about 3.5 to 4 centimeters wide, and the same age, 4 to 5 years. Relatively 
large specimens were employed to facilitate the recording of shell movements on the 
kymograph. That they were in good condition is shown by the fact that no control 
specimens died during experimentation. 
For laboratory use, liquor, through the courtesy of D. B. Davies, manager of the 
Rainier Pulp and Paper Co. at Shelton, Wash., was drawn directly from the digester 
at the end of a cook into a keg, in which it was transported and kept in the laboratory. 
The apparatus employed for the experiments is described in detail below. Most 
of the tanks, aquaria, etc., used were made of clear, transparent celluloid plates, one- 
eighth inch thick. Parts of any such piece of equipment were sealed together with a 
solution of the same celluloid in acetone. The material is well suited to such work 
and oysters live well in equipment made of it. 
A diagram of the apparatus used in the laboratory to produce a running mixture of 
liquor and sea water is presented in Figure 1. It is essentially an arrangement of 
constant levels whereby the rate of flow due to gravity is kept constant. In the 5-gal- 
lon carboy (A) was a mixture of liquor and sea water in proportions 1:4, 1 : 9, or 1 : 19, 
depending upon the final concentration desired. The tube in the mouth of the bottle 
projected into the jar ( B ) in such a manner as to cause liquor to flow down when the 
