THE ZooLoGIst—JuNE, 1876. 4945 
which, when ejected from the shell of the parent oyster, lay in a 
white mass at the bottom of the glass vessel. I immediately 
removed small quantities of the spawn with a dipping tube, and 
transferred them to separate vessels. Under the microscope each 
granule had the appearance of a white, opaque, heart-shaped 
motionless egg. In those vessels in which a larger quantity of 
spawn had been deposited, it soon died off, and in a few days most 
of it had become decomposed ; but in one vessel, which presented 
a large surface of water exposed to the air, and contained only a 
small quantity of spawn, the water remained bright and pure, and, 
after four days, the ova showed unmistakable signs of vitality, 
a slow, restless motion being perceptible on examination with the 
microscope. On the fifth day the motion was more rapid, and cilia 
were distinctly visible under the microscope. On the seventh day 
the embryos rose from the bottom of the vessel, and swam with 
increased rapidity. On the tenth day they had acquired shells, and 
presented exactly the appearance with which microscopists who 
have examined black spawn are familiar. Unhappily, I am unable 
to record any further progress made by my artificially-hatched 
oysters. Although I took care to supply them with suitable 
“cultch,” they could not make themselves at home, and died off 
miserably, after an active existence of some days’ duration. The 
same result has attended all my experiments even with mature 
and healthy spawn, and I am inclined to believe that that condition 
of weather which practical oyster-culturists are agreed is requisite 
to enable the young oyster to attach itself—viz., steady, warm and 
bright weather, with still, clear water—is also favourable to the 
production of certain elements which serve for the nourishment of 
the tiny creature, and in the absence of which it is starved, even 
though it be sheltered from the rough waves by artificial means. 
It will, of course, be understood that the emission of white spawn 
in the case described above was abnormal and unnatural, and it is 
no wonder that the mass of it died when removed from the parent 
shell, being thus deprived of the vivifying influence of the ciliary 
currents perpetually flowing over the branchiz of the oyster, within 
the folds of which the ova are intended to remain until they are 
brought to maturity. 
In spite of all that has lately been said and written about over- 
dredging, it is a fact that countless myriads of embryos are every 
year matured within the shells of native oysters on the grounds of 
