506 
BULLETIN OF THE BUREAU OF FISHERIES 
By examining Table 15, which contains all the data of oxygen consumption of 
oysters of known copper content, one can notice that the respiratory rate of the green 
oysters was slightly higher than that of the normal ones. It must be borne in mind, 
however, that high oxygen consumption was observed also in the normal oysters. 
(See Table 4, experiment 8.) Unfortunately, no copper determination of these 
oysters was made, but it is very doubtful if their copper content was high, because 
during the course of the investigation no normal oyster was found that had high 
copper content. While the relationship between the oxygen consumption and cop- 
per content can not be definitely established, the results of the present investigation 
indicate very clearly that the metabolic rate of the green oysters was at least equal 
to, and probably higher than, that of the normal oysters. The conclusion can be 
drawn that so far as the rate of metabolism is concerned, there is no indication of 
any disturbance due to the accumulation of copper. 
Table 15 . — The relation of the copper content of oysters to the oxygen consumption 
NORMAL OYSTER 
Experiment 
Date 
Oyster 
Dry 
weight 
Cu. mg. 
per 100 g. 
dry weight 
Cu. mg. 
per oyster 
Os consump- 
tion, c. c. per 
hour per 10 
g. dry weight 
10 
40-45 incl 
i 2.07 
1 2.08 
i 1. 875 
‘ 1. 275 
3 1. 8015 
/ a 8. 21 
1 8.26 
f a 9. 90 
\ 9.52 
/ 11.09 
\ 11.41 
/ 13. 26 
\ 12. 55 
13. 77 
a 0. 170 
0. 171 
2 0.206 
0. 198 
0. 208 
0.214 
0.169 
0. 160 
0.248 
} 6.45 
} 8.70 
} 9. 16 
} 10. 99 
9.86 
11 
Aug. 3_ 
46-51 incl 
12 
Aug. 6 - 
52-57 incl 
13 
Aug 9 
58-63 incl— 
75 
Aug. 21 
75 
GREEN OYSTER 
72 
Aug. 16 
72 
a 1. 1827 
175. 02 
2.07 
10.28 
73 
Aug. 17 - 
73 
a 1. 0188 
121. 71 
1.24 
11. 63 
76 
76 
a 1. 8830 
271. 91 
5. 12 
12. 09 
77 
Aug. 30- 
77 
a 1. 2494 
186. 49 
2. 33 
10. 74 
78 
Aug. 30 
78 
a 1. 2200 
175. 74 
2. 144 
12.25 
79 
Aug. 31 
79 
a 1. 0190 
241. 41 
2.460 
13. 47 
Note. — Closed chamber method used in experiments 10-13, inclusive. Open chamber method used in experiments 72-79, 
inclusive. 
> Average weight of 6 oysters. 
a Determinations were repeated wherever there was sufficient material. 
» Weights of individual oysters. 
SUMMARY 
1. Two methods for the determination of oxygen consumption of the oyster 
were devised. 
2. Oxygen consumption of normal oysters under standard conditions varies 
from 6.45 to 15.04 cubic centimeter per hour per 10 grams of dry weight. 
3. Oxygen consumption is not influenced by oxygen tension when the amount 
of oxygen present is greater than 2.5 cubic centimeters per liter. Below this point 
oxygen consumption is affected by oxygen tension. 
4. Changes in pH values such as can be brought about by the oyster under the 
conditions of the experiments and the accumulation of the products of its own 
metabolism do not alter its metabolic rate. The shell of the oyster acts as an effi- 
cient buffer, preventing the lowering of the pH below 6.0. 
5. Low oxygen tension and variation in the pH values of water from 8.2 to 6.6 
have no effect on the rate of flow of water through the gills. 
