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BULLETIN OF THE BUREAU OF FISHERIES. 
INTRODUCTION. 
In connection with experiments being carried on by the United States Bureau of 
Fisheries at its biological station at Fairport, Iowa, relative to the propagation of 
commercial species of fresh-water mussels, it became important to have as precise 
information as possible concerning the food requirements and the feeding processes 
of these mussels. With these considerations in mind, the investigations to be 
described hereafter were undertaken. Since any attempt at propagation must deal 
especially -with the young mussels, it is very essential to know exactly the feeding 
reactions of and the food required by the juvenile mussels that are being handled. 
In these investigations, therefore, especial emphasis has been laid upon the study of 
the juvenile mussels. 
The work was carried on by the senior author during July, 1921, at the United 
States fisheries biological station, Fairport, Iowa, and during August, 1921, at 
the Iowa Lakeside Laboratory, Lake Okoboji, Iowa, and by the joint authors 1 
during the summer of 1922 at the Fairport laboratory. During the latter season an 
unparalleled opportunity for the study of juvenile mussels was presented in the use 
of specimens of Lampsilis luteola and L. ligamentina, which were being reared in 
troughs in the highly successful propagation experiments conducted by Dr. A. D. 
Howard and B. J. Anson, of the Fairport station of the United States Bureau of 
Fisheries. Any desired quantity of specimens was freely placed at our disposal by 
these gentlemen, to whom we wish to express our gratitude. Thanks are due 
H. Walton Clark, also of the Fairport station, who very kindly supplied us with 
numerous specimens of juvenile mussels of various species which he collected from 
the river. 
The photomicrographs were taken by J. B. Southall, of the Fairport biological 
station. Figures 1, 2, and 6 were drawn by Edwin Meisenholder, a student of the 
senior author. Acknowledgment is made to Dean C. P. Lommen, of the depart- 
ment of biology, University of South Dakota, for reading the text and for suggestions. 
Opportunity is here taken to thank the United States Bureau of Fisheries for the 
financial support that rendered the investigations possible and to express our 
appreciation of the courtesies extended by It. L. Barney, director of the United 
States fisheries biological station, and by Dr. It. B. Wylie, director of the Iowa 
Lakeside Laboratory. 
HISTORICAL. 
An effort has been made to make the following review of the literature as com- 
plete as possible so far as food and feeding of fresh-water mussels are concerned. 
Reference is also made to a number of papers bearing on the same subject in other 
species of lamellibranchs on account of their bearing upon certain principles in- 
volved. For convenience the literature on the fresh-water mussels is dealt with 
first. 
1 The senior investigator is responsible for the work relating to the anatomical features of the mussels and the process of inges- 
tion, while the junior investigator studied especially the material ingested. 
