at present for measuring the efficiency of the ciliated mechanism alone 

 or for obtaining the over-all pictrore of the function of the entire 

 pimping system* Both methods have their own advantages and limitations, 

 which are briefly discussed below. 



The materials used in the tests were: Diesel oil, crude oil, water 

 extracts of these oils, and oil treated with carbonized sand. 



a* Effects on the efficiency of ciliated epithelium of the 

 gills (carmine cone method) : 



The slowing down of the work of the ciliated epithelium of the gills 

 by water soluble fractions of crude oil was first demonstrated in 

 1931-1932 by Galtsoff and Smith (Galtsoff et al., 1935, pp. 167-193) 

 using the carmine cone and the drop counting methods. In these methods 

 the functions of the adductor muscle and the mantle of the oyster are 

 eliminated and measurement is made of the efficiency of the pumping 

 mechanisms alone. The carmine cone technique is simple in operation 

 emd allows the accumulation of considerable data in a minimum of 

 experimental time. This advantage warrants its use for msiny purposes, 

 flie carmine cone method as used in these studies has been fully described 

 by Galtsoff et al. (1947) and by Chipman (1948). 



Oysters for these experiments were obtained from the Chesapeake 

 Bay close to the mouth of the Severn River. They were kept in sea water 

 tsmks for a period of several days to allow adjustment to laboratory 

 conditions. The salinity of the sea water varied from 14.09 to 14.70 parts 

 per thousand. All of the experiments were run at room temperature, which 

 ranged from 22. 2° to 26.0° C, but the greater number of tests were 

 carried on at 24° or 25° C. Fluctuations during any one experiment usually 

 did not exceed + 0,2° C» 



Comparison of the rate of pumping before and after the addition of 

 the test material was used as a basis for determining the effect. Control 

 oysters in non-polluted sea water were observed at the same time to check 

 any effects that may be due to other causes. 



The following prooediire was followed in conducting these tests: 

 The oyster, with the shell kept open by a small glass rod and with rubber 

 tubing inserted into the cloaoa, was placed in a large enamelware tray 

 containing five liters of water. The rubber tubing was then connected 

 to a glass tube for measuring the velocity of. current, and series of 

 measurements made during a period of two or more hours. Then the material 

 to be tested was introduced, the water well stirred, and the measurements 

 continued for several hours. In testing oil or oil extracts, the desired 

 volume of water was withdrawn from the tray and replaced by an eoual 

 volume of test liquid. The results, representing the mean of 10 consecutive 



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