Bull. U. S. B. F., 1921-22. 



I 1 , 71 —A floating crate containing four baskets (ci fig. k) in which were placed the fish infected with mussel glochidia. 

 The first successful attempt to rear mussels was made in this d< 



Fig. 75.— One ol the propagation baskets with the bottom -till submerged and photographed from directly above. 

 < iwing to disturbance of the water supply the young mussels, as shown by their trails, have migrated considerably. Such 

 migrations apparently do not occur under ordinary conditions. Reduced to two ninths natural size. 



