38 Our Food Mollusks 



tangled in the mass of mucus produced by the gland 

 cells of the filaments. 



Cilia now carry the mucus, with its captured organ- 

 isms, down to the margin of the gill, or in some cases to 

 its base, where it is passed forward along ciliated tracts 

 toward the palps. The palps, on touching the margin of 

 the gill with their inner ciliated surfaces, remove the 

 mass, which travels toward, and finally into the mouth. 

 In addition to aerating the blood, then, the gills have 

 become modified into food collecting and food trans- 

 porting organs also. 



The gills of the European oyster and several other 

 bivalves also, serve as baskets, in the female, into which 

 the eggs are discharged. Here they are held until they 

 have passed through the early stages of development. 

 This, however, does not occur in any of our Atlantic 

 food mollusks. 



