CULTURE OF FRESH-WATER MUSSELS. 65 



from a floating fish car to which were added barrels to give greater buoyancy. Four 

 baskets (fig. 75) of rectangular shape, i l /i by 2% feet, were made to fit inside. These 

 consisted of a framework of galvanized iron attached to a bottom tray of the same material , 

 both of which were painted with two or three coats of asphaltum to prevent corrosion. 

 On the frame was stretched copper cloth 100 meshes to the inch. In the baskets were 

 placed the fish infected with mussels. In order to reduce the length of time necessary' for 

 retaining the fish in such narrow confines, they were not placed in the crate until a few 

 days before the end of the parasitic period of the mussels and were removed as soon as 

 the mussels were shed. Plants of the following species of mussels were made from time 

 to time: The washboard, Quadrula heros (Say); the mucket, Lampsilis ligamcntina 

 (Lamarck) ; Lake Pepin or fat mucket, L. luteola (Lamarck) ; the yellow sand-shell, 

 L. anodontoidcs (Lea) ; and the pimple-back, Quadrula pustulosa (Lea). 



Modifications of the floating crates were introduced from time to time with a view- 

 to improvement of conditions for both fish and mussels and economy of operation. The 

 latest form of float (figs. 58 and 59) adopted is made from two cedar telegraph poles held 

 apart by crossbeams, 4 by 4 inches, at a distance sufficient to suspend lengthwise seven 

 crates having dimensions 3K by i l A by \ l /i feet. The crossbeams are placed at 4-foot 

 intervals, and to them are bolted strap-iron hangers by means of which the crates are 

 suspended. On the crossbeams over the telegraph poles are nailed 2-inch planks, 10 

 inches wide, forming a walk on each side the full length of the float. From this walk 

 two operators can conveniently raise the crates in which the infected fish are placed. 

 A float of this form was devised to protect the crates from wave wash and to give greater 

 stability in stormy weather, when a shorter and smaller float would be tossed about. 



The crates or baskets (fig. 60) in the improved type are constructed of cypress 

 lumber, being made as light as the demand for strength permits. The bottom or floor 

 is made of matched lumber and tight enough to prevent the escape of the microscopic 

 mussels. The superstructure consists of a framework, on the outside of which is nailed 

 galvanized screen of one-fourth-inch mesh. Fitted inside of the frame and outer screen 

 are the inner screens, which consist of wooden frames to which copper cloth is fastened 

 with copper tacks. The inner screens are removable, held in place by buttons or other 

 locking devices. The removable screens are so provided with overlapping strips as to 

 give a joint sufficiently tight to prevent escape of the small mussels. In the use of 

 removable wire screens the following objects were in view: It facilitated the cleaning 

 of the copper cloth and provided an opportunity to enlarge the mesh of the screens as 

 the mussels increased in size, thus giving them a freer flow of water and economizing 

 the higher-priced fine-meshed copper cloth. The use of wood instead of metal as 

 employed in the first baskets provided distinct and obvious advantages. Metal was 

 objectionable wherever the young mussels might come in contact with it, was less durable, 

 and was more expensive. Metal cloth could not be dispensed with entirely, because 

 other fabrics will not last under water. The increase in size of the crates or baskets 

 was of marked advantage in providing more room for the fish, thus permitting use of 

 greater numbers with less mortality. 



The whole assembly of float and crates provided a convenient and economical 

 means of operation greatly improved over the first crates, in which the raising of the 

 much smaller baskets was necessarily done from boats and in comparison was awkward 



