BULLETIN OF THE UNITED STATES FISH COMMISSION. 407 



of the paper soon became clogged with flue sediment, so as to stop the 

 flow of water. Bolting-cloth does not have the meshes fine enough to 

 hold the eggs ; besides, it is expensive and not durable. The use of a 

 membrane of filtering paper, with nickel-plated wire cloth above and 

 below the jiaper in order to strengthen it, and forming the bottom of 

 hatching-boxes placed inside of another and larger box from which the 

 sea- water was allowed to escape rapidly through an intermittently act- 

 ive siphon, and constantly run in very slowly, was found to clog, as in 

 apparatus where the flow was only in one direction. Although the 

 contrivance was automatic, as the outer box filled up, the inflow into 

 the inner box with the porous bottom containing the eggs was inter- 

 fered with both by the swelling of the fibers of the i^aper as well as 

 by the accumulation of slimy sediment in the substance of the latter. 

 The outflow from the inner boxes through their i^orous bottoms was 

 then impeded from -the same causes, and as the siphon emptied the 

 outer box the water in the inner boxes would not fall quickly enough 

 to efl'ect any considerable change. Filtering the water did not seem to 

 help matters sufficiently to make it an object to filter a supply for the 

 purpose. Here our experiments have broken down completely, and all 

 the results so far reached with such ajjparatus have not been of suffi- 

 cient value to make it desirable to repeat them in the same way, though 

 they have been conducted with three different forms of apparatus. 



Recently Prof. S. I. Smith, of Yale College, has succeeded in incubat- 

 ing the eggs of certain crustaceans in shallow plates without changing 

 the water at all, but by simply aerating and keeping it in constant cir- 

 culation by means of jets of air playing constantly upon its surface. 

 This mode of hatching appears to fulfill the requirements of the case 

 fully, as far as I can now see, and it will be of the greatest importance 

 to test this method at the earliest possible opi^ortunity. By its use we 

 will be enabled to avoid the loss of eggs which would follow from the 

 use of any method in which there is a current of water constantly run- 

 ning in and flowing out of the incubating contrivance. 



Should we be able to artificially incubate the eggs of the oyster and 

 keep them alive until the time when the embryos attach themselves to 

 foreign objects, we will have attained such a success as will probably 

 never be paralleled in any other branch of fish culture. The artificial 

 impregnation of the eggs of the oyster may be accomplished to the ex- 

 tent of thousands of millions ; and, should it be found possible to keep 

 their hosts of youug alive until they had passed certain critical periods 

 of their embryonic existence, we would have practically succeeded in add- 

 ing so many millions of spat to those already existing, from which seed 

 might be supplied for the foundation of extensive beds where oysters 

 had been previously unknown. 



Brooks, in carrying his embryos along for the period of six days, en- 

 countered the same difficulties as myself. If, as I have good evidence 

 for premising, when the young oyster ceases its wandering habit its 



