502 
BULLETIN OF THE BUREAU OF FISHERIES 
mined, 1 cubic centimeter of a 5 per cent solution of glucose was added to the water, 
and the rate of oxygen consumption was measured over a period of several hours; 
then another cubic centimeter of 5 per cent glucose was added. Usually after the 
addition of 3 cubic centimeters the oyster closed up and remained so until the water 
had been changed. 
It can be seen from Table 13 that the rate of oxygen consumption rose imme- 
diately after the introduction of the glucose, but it apparently reached its maximum 
very quickly, because subsequent increase in glucose was without effect until the 
concentration was sufficient to cause the oyster to close its shell. 
Table 13. — Effect of addition of glucose on oxygen consumption 
[September 6, Oyster No. 75] 
O 2 tension, 
O 2 consump- 
O 2 tension, 
O 2 consump- 
O 2 tension, 
O 2 consump- 
Time 
c. c. per 
tioD, c. c. per 
Time 
c. c. per 
tion, c. c. per 
Time 
c. c. per 
tion, c. c. per 
liter 0°, 
hour per 10 g. 
liter 0°, 
hour per 10 g. 
liter 0°, 
hour per 10 g. 
760 mm. 
dry weight 
760 mm. 
dry weight 
760 mm. 
dry weight 
11 00 
4. 65 
5.01 
7.00 2 
2.76 
12.38 
11.30 . 
4. 45 
5. 62 
5.30... 
4. 11 
13. 70 
7.01 
12.00 
8. 84 
6.01 2 
3.96 
14. 45 
7.30. 
2. 42 
13. 87 
12 30 1 - 
3. 78 
8. 84 
6.00 
8.00 3 
1. 98 
14. 12 
5 00 2 
4.62 
6.30 
3. 32 
1 Oyster closed, and experiment was discontinued for a few hours. Oyster opened at 5 p. m. 
2 1 c. c. of 5 per cent glucose added. 
3 Oyster closed. 
EXPERIMENTS WITH GREEN OYSTERS 
The problem why oysters become green in certain localities has attracted the 
attention of biologists interested in a scientific study of this phenomenon and of those 
concerned with the oyster industry. Inasmuch as a good review of the extensive 
literature on the subject can be found in the papers of Herdman and Boyce (1899) 
and Ranson (1927), it suffices to mention here only a few essential points that have 
direct bearing on the problem. The present investigation refers to those green 
oysters the color of which is associated with the accumulation of copper in their bodies. 
It does not concern the so-called green-gilled oysters (from marennes) the coloration 
of which is due to the absorption of the pigment of a diatom, Namcula ostearia. 
It has been demonstrated by Ryder (1882) that the green coloring matter of the 
American oyster is taken up by the amoeboid cells which aggregate in cysts under the 
epithelium of the body and on the surface of the gills. Ryder suggested that the 
green pigment in the leucocytes may be phycocyanine. Later on it has been shown 
by Herdman and Boyce (1897, 1899) that comparatively large quantities of copper 
occur in the green leucocytes and that the intensity of the green color of the oyster 
is in proportion to the amount of copper present. They found that green American 
oysters relaid in the waters near Fleetwood, England, contained on the average 2.63 
milligrams of copper per oyster, whereas normal oysters from the same source con- 
tained only 0.7 milligram of copper. Microchemical examination made by these 
authors proved that copper reaction coincided histologically with the presence of 
green leucocytes. The cause of green color was investigated by Colwell and Nelson 2 
who arrived at the conclusion that copper is responsible for the bluish-green color 
of oysters from Narragansett Bay and certain sections of Long Island Sound. A 
different view was held by J. Nelson (1915) who believed that the green color is not 
due to copper. 
2 Unpublished manuscript in files of U. S. Bureau of Fisheries, 
