STUDIES ON THE REPRODUCTION AND ARTIHCIAL 

 PROPAGATION OF FRESH-WATER MUSSELS. 



By GEORGE LEFEVRE and WINTERTON C. CURTIS, 



Professors of Zoology in the University of Missouri. 



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INTRODUCTION. 



The threatened extinction in the upper Mississippi River and its more important 

 tributaries of those species of the Unionidae whose shells have been taken in enormous 

 numbers in recent years, both for the manufacture of pearl buttons and for the pearls 

 which they occasionally contain, has led the United States Bureau of Fisheries to under- 

 take an extensive investigation of the possibility of artificially propagating the com- 

 mercial species and of devising practicable means of restocking depleted waters which 

 present favorable conditions for their maintenance. The general direction of the inves- 

 tigation has been placed in the hands of the writers, who for several years have devoted 

 as much time as their regular duties have allowed to the work, in certain important 

 phases of which, however, many others have collaborated. 



It was recognized at the outset that if the investigation was to be of any practical 

 value it must be wide in scope and must extend over a period of at least several years. 

 At that time much remained to be learned concerning the breeding habits and seasons 

 of the commercial species, the biological and physical conditions under which they live, 

 their distribution throughout the Mississippi Valley, and many other essential matters, 

 while it was yet to be discovered whether artificial propagation could be successfully 

 carried out. At the very inception of the work, therefore, a comprehensive plan was 

 outlined which was designed to include every subject that might bear even remotely 

 upon the central problem — the restoration of the exhausted mussel beds — and, although 

 many parts of this program have scarcely been touched, much progress has been made 

 in some of the more important lines. 



The plan of work contemplated, besides a thorough investigation of the conditions 

 under which artificial propagation might be possible, a detailed study of the life history 

 and ecology of the Unionidae, with special reference to the geographical distribution of 

 the group throughout the Mississippi Valley, the breeding seasons and habits, the 



85079°— Bull. 30—12 8 



