490 
BULLETIN OF THE BUREAU OF FISHERIES 
various organisms growing on them. In neither experiment was the effect of 
muscular activity eliminated. 
In the present investigation attempt was made to eliminate or control all these 
variables and to carry out experiments under standard conditions. The experiments 
were carried out at the United States Bureau of Fisheries laboratory at Woods Hole, 
Mass. Normal oysters used in the experiments were received from Onset Bay, 
Mass. Green oysters were obtained from the commercial beds near New Haven 
Harbor in Long Island Sound. All the oysters before being used in the experiments 
were kept for at least two weeks in floats anchored in Woods Hole Harbor. 
METHOD 
The method of study of the oxygen consumption of nonambulatory organisms 
like the oyster is very simple. The oxygen content of the water is determined under 
standard conditions before the animal is put in and at given intervals thereafter; 
the difference, representing the amount of oxygen consumed, is calculated per unit 
of time and per unit of weight. In practice, however, there are a number of inter- 
fering factors (organic matter in the water, organisms grown on shells, muscular 
activity, etc.) that must be controlled. 
Preliminary tests have shown that the sea water from the laboratory supply 
used in the experiment consumed appreciable quantities of oxygen. After it was 
passed through a K-inch asbestos filter its oxygen content, under the conditions of 
the experiments, remained constant over a period of 9 hours. (Table 1.) 
Table 1 . — Control experiment with filtered sea water. Closed chamber method 
Time, hours 
Oxygen, 
c. c. per 
liter 
Time, hours 
Oxygen, 
c. c. per 
liter 
o - 
4. 56 
5 
4. 69 
1 . 
4.62 
6 
4. 58 
2 
4. 58 
7 
4. 62 
3 
4. 60 
8_ 
4. 57 
4 . 
4.65 
9 
4.60 
The shells of the oysters were thoroughly scrubbed with a wire brush and then 
covered with paraffin. This treatment covered any remaining organisms and pre- 
vented the absorption of dissolved gases by the porous substance of the shell. A 
control experiment (Table 2) shows that during the period of 5 hours the oxygen 
content of the water, in which the shells treated in this way were kept, remained 
nearly constant. 
Table 2. — Control experiment with treated shells. Closed chamber method 
Time, hours 
Oj content, 
c. c. per liter 
Time, hours 
Oj content, 
c. c. per liter 
o _ . ... 
4.30 
3 
4.30 
1 
4.36 
4 
4.28 
2 _ . 
4. 34 
5 
4.28 
The control of the muscular activity presented a more difficult problem, which 
we attempted to meet in two different ways. At first the shells of the oysters were 
gently forced apart, great care being taken not to injure the mantle nor tear the 
