clsjns, like oysters, are capable of slowing down their activities to a 

 low mi nimum for rather protracted periods of time. In this way they may 

 reduce the immediate effect of unfavorable conditions. If the latter 

 prevail for a long time, clams eventually may be injxired since their 

 movements are rather limited. 



Specimens for testing were collected from Eel pond at Woods Hole. 

 They ranged in size from one to one and three-quarter inches in length. 

 A group of ten clams were placed in each of nine large finger bowls, 

 178 mm. in diameter. One bowl was used as a control, the remaining eight 

 receiving water contaminated with oil. 



The experiment was designed to test the effect of various types of 

 oil, either floating on the surface of water or mixed with carbonized 

 sand and sunk to the bottom. To avoid the placing of clams in close 

 proximinty to oil, the following arrangement was used: A large container, 

 through which the sea water was freely running, served as a common supply 

 from which the water was siphoned to eight beakers, each containing 20 ml. 

 of oil, or of a mixture of the same amount of oil with carbonized sand. 

 From each beaker the water was siphoned to the finger bowl with clams. 

 Overflow siphons kept the level of water in each bowl below the rim. The 

 flow was regulated to provide an exchange of water at the rate of 250 ml. 

 per minute (21 liters per hour). Four types of oil were tested; crude 

 oil, Diesel oil, lubricating oil, and fuel oil. During 12 l/2 days the 

 clams were examined each morning and evening and the number of those 

 with extended siphons wafi recorded. Protrusion of the siphons is a 

 reliable sign that the clam is active. This was corroborated by observ- 

 ing the accumulation of waste material, which was so great that it was 

 necessary to clean each bowl every other day. The record of the obser- 

 vations is summarized In table 18. None of the clams died during the 

 test and there was no evidence of their weakening. It was noticed that 

 the majority of clams had their siphons extended in the evening, but were 

 tightly closed each morning. This difference may have been associated with 

 the change in illumination, since the laboratory was becoming darkened at 

 the time of evening observations. There was no significant difference 

 between the behavior of clams in the control and in the water oontaminated 

 with various types of oil. 



If the experiments had been so arranged, close and intimate contact 

 m th oil might have produced toxicity in the experiments with tiie hard 

 shell clam, Venus mercenaria . This direct contact with the oil was 

 avoided, Thurlow Nelson, as quoted by Lane, Bauer, Fisher, and Harding 

 (1925, page 179), describes a mortality of soft shell clams (Mya) from 

 oil pollution as follows: "A most striking example of the efTects of 

 oil may be seen at low tide on the shores of Staten Island. On a wano 

 day, with consequent increased oxidation, soft clams (Mya) may be seen 

 cOTiing up to the surface of the flats by the thousands, dying soon after 

 reaching the top. The surface of the flats is covered by a heavy film 

 of oil, while the bodies of the animals reek with it. "Riis region. 



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