2i6 
BUI^IvETlN OF THE BUREAU OE FISHERIES. 
oxygen used by the shells. The shells of each oyster were at the end of the observations 
carefully cleaned in sea water and then used for two or three measurements of their 
oxygen-absorbing power at different temperatures. As these results were obtained 
under the same conditions as those expressed in table iii, they represent a fair estimate 
of the oxygen absorbed by the shells during measurements with the intact oyster. There 
is reason, as will be shown below, to believe that oxygen removed from the water in this 
way is not utilized by the active tissues of the oyster. It seems reasonable, therefore, 
to subtract the amount (measured or computed) of oxygen utilized by the shells from 
that used by the whole oyster before computing the oxygen requirements per gram of 
dried tissue. 
Table III. — Oxygen Used by Oysters. 
Note.— F igures in parentheses are averages of measurements under approximately uniform conditions. 
Weight, 
Decimilligrams oi oxygen used 
per hour. 
Averages of same per hour per 
100 grams. 
W eight, 
Average decimilligrams used per 
hour per gram of dried weight. 
whole 
oyster. 
At 
20® to 
20.5° c. 
At 
22® to 
22.5® c. 
At 
24® to 
24.5° c. 
At 
26° to 
26 .s°C. 
At 
20^ to 
30 .S°C. 
At 
22® to 
22.5°C. 
At 
24® to 
24 .s°C 
At 
26° to 
26.5° C. 
dried 
oyster. 
At 
20® to 
20.5® C 
At 
22° to 
22.S°C. 
At 
24° to 
24 .S°C. 
At 
26' to 
26 .s‘'C. 
Grams. 
47-8 
10. 6 
12. 2 
14. I 
(13- 1) 
14. 2 
17 - I 
22. 2 
27. 4 
29 - 7 
35 - 7 
Grams. 
1-15 
7.92 
9 - 74 
10. 40 
12. 90 
73 - 5 
16. 6 
20. 0 
17 - 5 ^ 
(18.3) 
23 - I 
18.3 
(20. 7) 
22. 0 
22. 6 
25. 0 
28. 2 
30. 0 
I. 66 
8. 20 
8. 61 
9 - 43 
9 - 59 
153-0 
19. 4 
22. 4 
21.4 
21. 7 
24 - 5 
(22. s) 
25. 2 
2 S- 9 , 
(25- 5) 
12. 7 
14. 6 
14 - 7 
16. 6 
2. 36 
5-98 
6. 78 
6. s6 
7 - 15 
173.0 
23-5 
24 - 5 
24. 7 
(24. 6) 
29. 2 
30. 8 
(30- 0) 
39-0 
34 - 3 ^ 
(36. 6) 
13-6 
14. 2 
17- 3 
21. 2 
3-64 
3-49 
4. 00 
4 * 53 
6. 10 
Average. 
17 - 5 
19. 7 
21. 9 
25-3 
17. 8 
20. 3 
23 - 5 
25-9 
6. 41 
7. 28 
7 - 73 
8. 94 
A graphic representation of the oxygen utilization of oysters at different tempera- 
tures is given on page 217. The ordinates represent decimilligrams of oxygen used 
per hour and the abscissae are degrees Centigrade. The full lines represent measure- 
ments on intact oysters. Curve i is constructed from the averages of the oxygen utiliza- 
tion per hour per 100 grams in experiments on nine oysters as summarized in table ii. 
Curve II is constructed from similar averages of experimental results on four oysters as 
shown in table in. Curve iii is based on the same results used for curve ii, but repre- 
sents the averages of oxygen used per hour per gram of dried shell contents. The rela- 
tionship between oxygen and temperature is apparently a simple one. The interrupted 
lines represent measurements on empty oyster shells showing the decimilligrams of 
oxygen used per hour by shells as recorded in table iv. Curves a, h. c, and d refer, 
respectively, to shells weighing 47.8, 73.4.. 153, and 161 grams. The effect of tempera- 
ture on the three larger shells seems to be fairly constant; their curves are parallel. 
The discrepancy in the smallest shell may be due to experimental error as so few deter- 
minations were made. 
