162 
BULLETIN OF THE BUREAU OF FISHERIES 
act as a filter and prevent many food organisms from reaching the oysters in the experi- 
mental tanks. 
Figure 3.— Cross section of apparatus used to expose oysters to sea water passed through oil and smudge. A, sea water intake; 
B, glass cylinder containing 1 liter of oil; C, siphon tube; D, oysters; and E, overflow. 
Table 2. — Survival of oysters in sea water passed through oil 
Total number of live oysters 
Percent survival ac- 
cording to size 
Apr. 30 
May 30 
June 30 
July 27 
Large 
Small 
Tank no. 1 (control— no oil) 
50 
39 
29 
23 (12 large, 11 small) 
48 
44 
50 
37 
24 
18 (11 large, 7 small) 
44 
28 
Tank no. 3, Barre oil B 
50 
38 
29 
21 (11 large, 10 small).. _ _ 
44 
40 
Tank no. 4, Pelto oil.. 
50 
30 
25 
do 
44 
40 
IMMERSION OF OYSTERS IN OIL 
The purpose of these experiments was to immerse oysters in crude petroleum at 
regular intervals in order to determine if they would be killed by direct exposure to oil 
or would subsequently recover from such severe treatment. By means of an artificial 
Figure 4 .— Diagram of apparatus used to immerse oyster in oil at regular intervals. A, control jar; B, automatic siphon jar; C-F. 
experimental jars containing different grades of petroleum and sludge; Q, sea water intake; H, oysters (4 per jar); I, vertical 
movement of oil layer during each artificial tidal cycle. 
tidal arrangement a heavy surface film of oil was made to cover completely the oysters 
at intervals of 1 and 2 hours. The equipment used, as shown in figure 4, consisted of 
