EFFECT OF CRUDE OIL POLLUTION ON OYSTERS 
171 
All experiments reported below were made during November and December 
1933 and from June through September 1934. It was thus possible to observe the 
reaction of oysters to the experimental fluids over a temperature range of from 10 to 
30 degrees centigrade and water salinity varying from 27.5 to 36.6 parts per million. 
The crude oil, collected by the Louisiana Department of Conservation from the 
Lake Barre and Lake Pelto wells of the Texas Co. in Terrebonne Parish, was shipped 
to the laboratory and kept in glass containers. The feeding activity of the oyster 
was determined by measuring the rate, and quantity of water pumped through the 
gills by the ciliated epithelium. 
CARMINE CONE METHOD 
The carmine-cone and the drop-counting methods developed by P. S. Galtsoff 
were used. The data obtained by these methods may be expressed as volume of 
water pumped or work performed. The carmine cone method, while not so accurate 
as the drop counting, has the advantage of being simpler and is better suited for 
experiments extending over several days. It has been fully described by Galtsoff 
(1928). Only a brief resume follows. 
The oyster is prepared by carefully forcing the valves apart and inserting a short 
piece of glass rod to hold them open. A 4-inch piece of gum rubber tubing of % inch 
inside diameter is pushed a short distance into the outlet of the gill chamber. Cotton 
is then used to close the opening between the valves so that no water can escape from 
the exhalent chamber except through the tube. 
The oyster is placed in an enameled rectangular tray approximately 14 inches 
by 20 inches by 2% inches, having a capacity of 7 1. A constant level arrange- 
ment maintains the level at 5 1 (5.25 quarts). An inverted T-tube is supported so 
that one of the arms may be connected to the prepared oyster and the other with a 
20 cm piece of glass tubing of 6 mm bore, marked off with a 10-cm interval. The 
shank of the inverted T is connected to a glass funnel by a short length of rubber 
tubing. The funnel contains a suspension of carmine in sea water. 
In operation, laboratory supply sea water flows through the tray at a rate of 
about 200 cc per minute. This flow is stopped at the beginning of an experiment. 
Circulation and aeration are accomplished by a stream of air bubbling through 
an inclined piece of glass tubing about 18 inches in length and l / 2 inch in inside diameter. 
After a preliminary period of half an hour to allow the oyster to adjust itself to 
the new conditions, it is considered ready for the experiment. A small amount of 
freshly made carmine suspension is admitted from the funnel and forms at the axis 
of the tube a cone which is carried out by the current from the oyster. By means of 
a stop watch, a measurement is made of the time, in seconds and tenths, required 
for the tip of the cone to traverse the graduated 10-cm. distance. As the 
mean velocity of the whole cross-sectioned area of the tube is one-half of the velocity 
at the axis (Galtsoff, 1928), the rate of discharge of water can be easily computed. 
No such computation was regarded necessary for the purpose of the present experi- 
ments, the results of which are presented as velocities of current in millimeters per 
second. 
Each time 10 or more readings were made and the average taken as representative 
of the velocity of current of water at the axis of the tube. Observations are made 
