File:Studies on the reproduction and artificial propagation of fresh-water mussels (1912) (14598139320).jpg

Identifier: studiesonreprodu00lefe (find matches)
Title: Studies on the reproduction and artificial propagation of fresh-water mussels
Year: 1912 (1910s)
Authors: Lefevre, George, 1869- Curtis, Winterton C. (Winterton Conway), 1875-1965
Subjects: Freshwater mussel culture
Publisher: Washington, Govt. print. off.
Contributing Library: The Library of Congress
Digitizing Sponsor: Sloan Foundation

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of fish with constant and uni-form results. We have tried, though not very extensively, two means of effecting 166 BULLETIN OF THE BUREAU OF FISHERIES. this. The first consisted of a two-bladed propeller fastened in the middle of the bottomof a tub and rotated slowly, there being enough space in the water above the blades toallow the fish room to escape the stroke. This device was not very satisfactory, butas it was operated by hand and the blades roughly constructed, effective use might bemade of a more carefully adjusted mechanism of this type. A second and morepromising device consists of a branched system of iron pipes bored with many smallholes (text fig. 3), through which fine jets of water are forced out at the bottom of atank. The amount of pressure in these fine jets can be easily regulated from the mainsupply pipe, and the height to which the glochidia will be driven from the bottom isthus controlled. The tank may be allowed to overflow at the top and the glochidia -<r-^S
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Fig. 3.—Apparatus for keeping glochidia suspended in water while fish are being exposed to them for gill-infections. Tapwater entering at S issues in fine jets through the very small holes placed along the top and sides of the pipes on the bottomof the aquarium, and an even distribution of glochidia throughout the water is thereby maintained. By regulating theforce of the water entering the pipes at S the glochidia are prevented from rising to the top of the aquarium and escapingwith the overflow. prevented from being carried off in the overflow by so adjusting the force of the jetsthat the glochidia will not rise quite to the surface. This device keeps the glochidiasuspended in a very uniform way, and it may prove to be just what is needed for theuniform infection of large numbers of fish. CONDITIONS NECESSARY FOR SUCCESSFUL INFECTION. Three factors should be considered in attempting the infection of any species offish with glochidia, namely, the uniform suspension of the glochidia

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