46 American Fisheries Society 



juveniles to a size of 3 mm., the largest which has been 

 recorded so far as I know. 



Having had about the same indifferent results as other 

 investigators in such attempts, it seemed to me that a 

 promising line of attack for a solution 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. In our situation, where we take the 

 mussels from the Mississippi, the most practicable solu- 

 tion that offered itself to me was a floating crate contain- 

 ing baskets of sufficient size to hold the fish and made of 

 small enough mesh to retain the microscopic mussels. 



A crate thus held at the surface accommodates itself 

 to the frequent rise and fall of the river, is convenient 

 of access and removes the young mussel from many of 

 its enemies at the bottom. Another advantage of a sur- 

 face location is that the precipitation of silt is at a mini- 

 mum. The crate was constructed from a floating fish 

 car to which were added barrels to give greater buoy- 

 ancy. Four baskets of rectangular shape were made to 

 fit inside. These consisted of a frame work of galvanized 

 iron attached to a galvanized iron bottom tray. On the 

 frame was stretched copper cloth of one hundred mesh 

 to the inch. 



Two or three weeks after obtaining the plant of young 

 mussels from the bass, I found evidence that they were 

 thriving in the crate. A small sample of sediment from 

 the bottom revealed some half dozen or more, and at va- 

 rious intervals during the summer, I readily obtained 

 specimens, making observation on rate of growth and 

 preparing material for anatomical studies. At the last 

 observation in September, the young mussels were about 

 an inch in length (twenty-five millimeters). This com- 

 pares very favorably with the length of 3 mm. secured 

 by Karl Herber. 



For comparison, I put some of the rapidly growing 

 mussels from the crate in an aquarium of running water 

 and compared their growth for a period of three weeks 

 with those growing at the same time in the crate. I 



