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BULLETIN OF THE BUREAU OF FISHERIES 
different methods and apparatus, a description of which is furnished with each series 
of experiments. Special studies were also made of the changes in glycogen content 
of oysters after continuous exposure to three different grades of crude petroleum 
and varying concentrations of brine water from the Barre wells. The glycogen 
analyses were performed by P. S. Galtsoff. 
EXPERIMENTS WITH SURFACE FILM OF OIL 
The shell movements of the oyster indicate whether it may or may not be feeding 
and also reflect quite accurately its reactions to environmental conditions. Graphic 
records were obtained of the shell movements of one representative oyster in each of 
the experimental and control jars. For this purpose adult oysters of approximately 
the same age and size were immobilized in a horizontal position by cementing the 
lower valve to a brick or piece of slate. The upper valve was free to move, and, by 
means of a simple arrangement of levers and pen, its movements were transmitted 
and recorded continuously on a revolving smoked drum as shown in figure 2. 
Figure 2.— Diagram showing arrangement of apparatus for obtaining comparative records of shell movements of oysters in sea 
water (control) and in sea water passed through oil (experimental). A, light muscle lever; B, aluminum pen; C, counterbal- 
ance weight; D, constant level arrangement; E, rubber universal joint and light rod connecting upper valve of oyster to 
recording pen; F, oyster cemented to brick (control); G, kymograph; H, layer of oil; and I, experimental oyster. 
A series of experiments was arranged, employing 5 glass jars of 6-liter capacity, 
in each of which 2 small and 2 large adult oysters were placed, 1 of the latter being 
attached to the recording apparatus. Four of the jars were covered with a heavy 
surface layer (50 cc) of the following oils and sludge — grade A and grade B crude 
petroleum from the Barre wells, a composite sample of crude petroleum from the 
Pelto wells, and basic sludge collected from the storage tanks at the Barre wells. 
Each experimental jar was supplied with running sea water, which was introduced 
above the oil film at the rate of 8 liters per hour as shown in figure 2. This series 
of experiments was conducted from July 3 to September 4, 1933, during which time 
the surface layer of oil and sludge was renewed weekly. The temperature of the 
water ranged from 24.8° C. to 28.5° C., and the salinity from 32.7 to 33.4. 
The results of these studies are shown in table 1. All of the large adult oysters 
survived, and those attached to the recorder and exposed to oil and sludge showed 
essentially the same behavior as the control in respect to shell movements and ability 
