18 
through a siphon, reaching nearly but not quite down to the 
eggs. A fresh supply of sea water should then be added, and 
the eggs stirred and allowed to settle, and the water drawn 
off as before, and this should be repeated until the water, 
after the eggs have settled to the bottom, remains clear. 
The beaker may now be set aside where it will not be ex- 
posed to sudden changes of temperature, and the eggs wdll 
require no further attention until the embryos begin to swim, 
which will be in from two to six hours, according to the tem- 
perature. The little oysters must of course be supplied with 
fresh sea water from time to time during their development, 
and as they are so small that the water cannot be drawn off 
after they begin to swim, they must be supplied with fresh 
water by transferring them from time to time to larger and 
larger beakers. In two hours or so after the eggs are fertil- 
ized the embryos begin to swim, and crowd to the surface of 
the water in great numbers, and form a thin stratum clqse to 
the surface. This layer of embryos may be carefully siphoned 
off into a very small beaker, and a little fresh sea water 
added. In an hour or so there will be a new layer of em- 
bryos at the surface of beaker Ho. 1, and these should also 
be siphoned into Ho. 2, and this should be repeated as long 
as the embryos continue to rise to the surface of the first 
beaker. Every five or six hours a little fresh sea water should 
be poured from a height of a foot or more into beaker Ho. 2, 
until it is filled. The contents should then be poured into a 
larger beaker, and sea water added four or five times a day as 
before. In this way the embryos may be kept alive for a 
week, although they have by this time got into such a large 
vessel that it is almost impossible to find any of them for 
microscopic examination. 
THE DEVELOPMENT OF THE EGGS. 
I will now attempt a brief popular account of the changes 
thro igh which the fertilized egg is gradually converted into 
the complex body of the adult oyster. 
