THE BLOOD OF NORTH AMERICAN FRESH-WATER MUSSELS 
UNDER NORMAL AND ADVERSE CONDITIONS 1 
By 
M. M. ELLIS, Ph. D., In Charge Fishery Investigations Interior Waters 
AMANDA D. MERRICK, A. M., Temporary Assistant 
and 
MARION D. ELLIS, A. M. 
CONTENTS 
Page 
Introduction 509 
Normal blood of fresh-water mussels 510 
Method of taking samples 510 
General physical properties 511 
Specific gravity 511 
Total solids and ash 514 
Blood sugar 516 
Inorganic salts 517 
Hydrogen-ion concentration and buff- 
er values 518 
Blood gases 520 
Verification of blood-salt values by the 
foot-strip method 521 
Page 
Changes in blood of living mussels induced 
by environmental factors 523 
Effects of changes in salt content of 
water 524 
Distilled water 525 
Sodium salts 528 
Potassium salts 530 
Magnesium salts 532 
Calcium salts 533 
Effects of exposures to air 535 
At ordinary temperatures 535 
Near freezing 538 
Summary 539 
Bibliography 540 
INTRODUCTION 
In the course of field studies on the mussel beds of the upper Mississippi, con- 
ducted during the past three years, considerable numbers of dead and dying mussels 
have been found in various localities once very productive of commercial shells. In 
addition, a large per cent of the glochidia, taken from female mussels living in the 
same areas, have been dead or diseased, indicating the existence of conditions which 
are reducing the natural reproduction of even such adult mussels as are able to with- 
stand the environment. It is well established that progressive changes in stream 
conditions, resulting from the needs of navigation and from contamination through 
municipal and industrial wastes, have materially altered the natural habitats of the 
fresh-water mussels at many points in the Mississippi drainage. In order to evaluate 
the effects of these changes on the mussel fauna, particularly the effects of municipal 
and industrial wastes on the mussels themselves, a series of physiological studies on 
fresh-water mussels has been undertaken. 
In the fresh-water mussels the blood is associated not only with nutrition, respira- 
tion, excretion, and the general well-being of the individual as in the higher animals, 
but the blood also has a special mechanical function in connection with the peculiar 
locomotion of fresh- water mussels. The “ foot,” the muscular organ of locomotion 
1 Submitted for publication June 26, 1930. 
509 
