312 Our Food Mollusks 



ously plowed or raked in order to loosen its surface. 

 Ordinarily this would not be necessary. 



Larger seed might perhaps be successfully plowed un- 

 der, but no experiment besides that at Bridgeport has 

 been made to test it. In the U. S. Fish Commission ex- 

 periments, clams were dropped into holes made with 

 stakes. On a pebbly beach where the making of the hole 

 was very difficult, four men at one time thus planted three 

 thousand clams in two hours. Subsequently on a sandy 

 bottom the work was accomplished three or four times 

 as rapidly. It would not be difficult to construct wheels 

 with pegs on the rims that would make rows of de- 

 pressions as rapidly as desired. Such a method of plant- 

 ing clams would ensure their lodgment and their proper 

 distribution, and the labor required ordinarily would not 

 be great. 



After attaining a length of more than two inches, the 

 soft clam is soon injured by exposure in summer. Tem- 

 perature, however, and not merely exposure, is the im- 

 portant factor. For several days the animal is able to 

 withstand temperatures near the freezing point appar- 

 ently without injury, but it lives only a short time out of 

 the water in warm weather. Experiments show that an 

 exposure of forty-eight hours during the hottest part of 

 the summer will lead to the death of the majority, even if 

 they are then planted, but few perished on being exposed 

 twenty-four hours under the same conditions. 



Clams to be planted, however, should ordinarily be 

 much smaller than this, and the power to resist heat in- 

 creases as size diminishes. When kept in aquaria sup- 

 plied with running water, large clams live only a few 

 days when the weather is warm; but those less than half 

 an inch long have been kept alive in a hot room, barely 



