12 



TJ. S. BUREAU OF FISHERIES. 



covered with a 2-inch layer of fine white sand and the rate of flow 

 through it was regulated by the valve e. The half barrel was filled 

 with water up to about 6 inches over the sand and freshly fertilized 

 eggs placed in it. A fine stream of water from the faucet a kept up 

 a constant circulation in the barrel from the time the eggs were put 

 in. Tests from time to time at the drain e indicated that none of the 

 eggs were passing out through the sand or filtros, but as no trace 

 could be found of the embryos in the barrel above the sand layer it 



» a 



Fig. 6. — Barrel equipped for developing oyster embryos to tlie shell stage. 

 a. Fine stream for supplying salt water and circulation in the barrel ; 

 ft, salt water containing embryos ; c, 2-inch layer of fine sand ; d, filtros 

 block ; c, drain pipe with control valve, 



was thought at first that they had died and that the apparatus was 

 a failure. However, after a period of 48 hours, it was decided to 

 wash out the sand and try a new batch of spawn. In turning a 

 heavy stream of water into the barrel and opening wide the valve e 

 it was found that thousands of vigorous larvae with well-developed 

 shells were washed out into the triple layers of bolting silk placed 

 there. This was indeed encouraging, as the filtros blocks ^yere suit- 

 able for rearing them once they had developed shells. This experi- 

 ment was repeated several times with success and it is to be regretted 

 that the lateness of the season prevented carrying the laryoe through 

 to setting and making the summer's work one of production as well 

 as theory. 



