FOOD AND FEEDING IN FRESH-WATER MUSSELS. 
By 
E. P. Churchill, Jr., Department of Zoology, University of South Dakota, 
and 
Sara I. Lewis, Department of Botany, University of Iowa. 
CONTENTS. 
Page. 
Introduction 440 
Historical 440 
Fresh-water mussels 441 
Lamellibranchs in general 445 
Materials and methods 446 
Ingestion 446 
Observations and, experiments 447 
Mussels 0.2 mm. long 447 
Mussels 0.28 mm. long 448 
Mussels about 1 mm. long 448 
Mussels 2 to 2.5 mm. long 450 
Mussels 3 mm. long 452 
Mussels feeding in heavy suspensions 453 
Mussels 4 mm. long 454 
Mussels 12 mm. long 455 
Mussels over 12 mm. long 456 
Study of sections of the palps 457 
Adult mussels 457 
Theory of the function of grooves on ridges of palps 458 
Longitudinal groove on faces of palps 459 
Conclusions 459 
Food 460 
Juvenile mussels 460 
Adult mussels 461 
Feeding experiments 462 
Inorganic material 462 
Organic material 464 
Broken filamentous material 465 
Time required for passage of food through the alimentary canal 466 
General conclusions 466 
Bibliography 469 
Fresh-water mussels 469 
Lamellibranchs in general 470 
439 
