82 REPORT OF THE COMMISSIONER OF FISHERIES. 
a method of artificially producing these fattening beds in localities 
where they do not naturally exist. 
A bight of Lynnhaven Bay, embracing a water area of 2.6 acres 
and an average depth of about 2 feet, has been cut off from the open 
waters of the bay by a dam, excluding all but the highest storm tides. 
The food of the oyster consists mainly of microscopic plants, of much 
beauty of form and color and remarkable motility, known as diatoms. 
These, like the higher plants, are dependent for their growth or mul- 
tiplication upon the supply of inorganic salts in the water. Ordinarily 
this is obtained by the natural drainage from the land, and consequently 
oyster food is generally more abundant in the neighborhood of the 
mouths of streams having rich and extensive drainage basins. Warmth 
during at least a part of the year is also an important factor in the 
multiplication of diatoms, and consequently shallow waters, rather 
than deep ones, are usually better for fattening beds, other conditions 
being equal. Under the system in vogue in France shallow ponds 
apparently of themselves satisfy the conditions, but this was not the 
case at Lynnhaven. There was evidently a dearth of useful saline 
constituents in the water, and to supply this commercial fertilizers 
were introduced. The result was prompt, and there was an almost 
immediate increase of diatomaceous growth in the pond. 
This abundance of food having been secured, oysters were placed 
in various parts of the pond, but the results were mainly negative, and 
a study of the conditions indicated that this, in a measure at least, was 
due to the absence of currents to waft the food within reach of the 
sessile oysters. In the following year a remedy was found. At one 
side of the pond, or claire, a canal 150 feet long and about 8 feet wide 
was constructed of sheet piling. A circulation of water through this 
canal, and returning via the open waters of the pond, was secured by 
the use of a propeller operated by means of a gas engine, thus simu- 
lating the conditions supplied on the natural beds by tidal movements. 
The result of this arrangement was very satisfactory, and oysters 
placed in the canal were fattened, in some cases within a period of 
eight days, much improving their value on the market. 
New difficulties were encountered, however, and to the present time 
these have not been removed. There developed at times in the fat- 
tened oysters a decidedly marshy taste, which was eventually traced 
to an abundant growth of filamentous algze in certain portions of the 
claire. The same saline richness of the water which proved so favor- 
able for the diatoms was equally favorable to the growth of other 
vegetable matter. It was found that a limited application of lime 
water retarded or destroyed the algal growth, but it was necessary to 
exercise constant watchfulness and frequently the affection would 
develop suddenly and stop the shipment of oysters at a time when 
they were bringing the best prices. During the present year it was | 
