THE CLAM. 31 



but any absurd thing may be expected in a creature 

 whose ears and brains are about its foot. Still another 

 fact is brought to light through the microscope. For 

 both air and food, the clam must have an almost con- 

 stant stream of water running into it ; and to carry 

 away the food it rejects, and the impurities of its 

 blood, it must have a steady stream going out. 



To keep the water moving both in and out, the in- 

 side of the siphon is covered with minute hairs which, 

 by constant motion like- little paddles, pull and push 



Fig. I. Showing the Clam -within the Shell. 



the water along. The gills are covered by these hair 

 paddles. The mouth is surrounded by them, and all 

 together they keep the water in motion. In the out- 

 flowing siphon the same kind of hairs work the other 

 way, and move the waste water out. 



What now is meant by the saying, " As happy as a 

 clam"? Like the sponge, the clam never goes in 

 search of food. The food must come to the clam. 

 When the ocean tide is out, the clam is left in its hole 

 on the dry beach. It grows hungry during the six 

 hours of low tide. Up near to the top of the hole it 



