64 BULLETIN OF THE BUREAU OF FISHERIES. 



In aquaria, either balanced or supplied with running water, they did not seem to thrive. 

 Even in tanks out of doors supplied with water from their usual habitat the results 

 were negative. The majority apparently at the very beginning of their free life were 

 eaten by predacious forms, or, if by chance they escaped these enemies, they continued 

 their existence dwarfed. Something in the environment was unfavorable to them. 



Among European investigators who have attempted to rear young mussels are the 

 following, with the results attained as to time carried under culture: F. Schmidt (1885), 

 4 weeks; G. Schierholz (1888), 4 to 5 weeks; W. Harms (1907), 7 weeks; and Karl Herbers 

 ( I 9 I 3>), about 2 months, or to a size of 3.13 millimeters. 



In America we have the following records of artificially reared mussels. Lefevre 

 and Curtis (19 12) found a young mussel two years after a plant had been made in a 

 tank. Similar results were attained at the U. S. Fisheries Biological Laboratory at 

 Fairport, Iowa. In this case two mussels, Lampsilis venlricosa (Barnes), were obtained 

 in a pond one year after a recorded plant had been made. In these two instances no 

 observations of the mussels were made in the period between the planting and finding 

 of the mussel at an advanced stage of development. A. F. Shira (report in MS.) reared 

 the Lake Pepin mucket in a balanced aquarium to a size of 4.4 millimeters. 



As a part of the general plan mentioned above, the experiments described in this 

 paper were carried on to test the possibilities of artificial culture of mussels from the 

 earliest stages up to the mature adult. The studies were carried on at the U. S. Fish- 

 eries Biological Laboratory at Fairport, Iowa, under the direction of Dr. R. E. Coker, 

 in charge of the investigations upon the fresh-water mussels, and later under A. F. 

 Shira, his successor. The author wishes to acknowledge here courtesies extended and 

 assistance rendered in the conduct of these studies to the Crerar Library, of Chicago, 

 for use of their excellent facilities; to Bryant Walker, Detroit, Mich., for assistance in 

 determination of mussels; to Caroline Stringer, Omaha, Nebr., and Ruth Higley, Grand- 

 view, Iowa, for determination of Rhabdocools; to Prof. Edwin Linton, Washington, Pa., 

 for assistance in the determination of Turbellaria ; and to Prof. F. B. Isley, Fayette, Mo., 

 for suggestions of methods. 



METHODS AND PLAN OF INVESTIGATION. 



After some little experimental study of developing mussels it was realized that 

 there must be some vital deficiency under artificial conditions to account for the many 

 failures in attempts to raise mussels. It seemed that a promising line of attack in solu- 

 tion of the problem would be to find some way which would depart from the natural 

 habitat only so far as the necessity of mechanical control demanded. To rear at least 

 one brood of the young seemed to be an objective of prime importance. Success in 

 this would answer some unsolved questions as to growth, as well as furnish a starting 

 point for more artificial methods if these were desirable. In our situation, where we 

 take the mussels from the Mississippi River, the most practicable solution that offered 

 itself was a floating crate containing baskets made of wire cloth of sufficient size to hold 

 the fish and of a mesh small enough to retain the miscroscopic mussels. 



A crate held at the surface accommodates itself to' the frequent rise and fall of the 

 river, is convenient of access, and removes the young mussels from many of their enemies 

 prevalent at the bottom. Another advantage of a surface location is the fact that the 

 precipitation of silt there is at a minimum. The first crate used (fig. 74) was constructed 



