[69] OYSTER CULTURE. 821 
the necessary working of the ponds will permit, certain forms of-sub- 
marine vegetation, which should be planted upon the rock-piles and 
bottoms of the ponds. As arule plants of a green color should be chosen. 
Marine plants act in the water in the same manner that land plants do 
in the air. While men and animals absorb oxygen in breathing, and 
throw off carbonic acid, a noxious and suffocating gas, land plants, on 
the contrary, absorb the carbonic acid gas and decompose it, assimilating 
the carbon and exhaling the pure oxygen. In the same manner aquatic 
plants absorb the noxious gases produced by the respiration of aquatic 
animals and the fermentations going on in stagnant water, decompose 
them, and while storing up the carbon exhale the oxygen, which by dis- 
solving in the water gives it its vital properties. It is necessary, how- 
ever, to exercise some choice in selecting marine plants, since some of 
them grow with such rapidity and spread to such an extent that they 
- would soon interfere with, if not destroy, the culture they are designed 
to promote. To prevent this extension with such plants as may be 
chosen, it is well to introduce into the ponds some of those univalve 
mollusks which feed exclusively upon marine vegetation, and they will 
keep in check any excessive growths. 
One can also divide the basins into compartments, to separate the dif- 
ferent species and facilitate their capture at the time of sale. In fact the 
claires themselves can be used simultaneously for different species of 
crustaceans or other animals, excepting always those like the crab, &c., 
which would feed upon the oysters. 
One single example will suffice.. The morass of Kermoor, converted 
by M. de Cressoles into a salt lake about 70 hectares in extent and sur- 
rounded by salt meadows or lands formed by the mud dug from the 
lake, contains at the present time seventy thousand adult lobsters, which 
flourish in this miniature ocean as well as could be desired. There are 
also in this same lake hundreds of turbots which prophesy by their size 
and rapid growth a complete success for this magnificent experiment. 
In a word, and to sum up the various advantages of this kind of labor, 
so far as regards marine species, the owner of claires is in the same 
position as the agriculturist with his farm, his stables, and his meadows. 
He can multiply, rear, and fatten a large majority of the edible marine 
species, and, like the agriculturist, he should, as a good administrator, 
allow no portion of his domain, so far as is possible, to remain vacant or 
unworked. He should draw a revenue from everything, and while we 
have spoken here only of those species which are of considerable im- 
portance as marketable commodities, yet there are thousands of other 
marine species, fish, crustaceans, and mollusks which form only arestricted 
branch of commerce in those sections where they are taken, and which 
the possessors of claires might cultivate. By the rapid means of trans- 
portation to all the markets of France, they would become important 
sources of profit. Despite the immense impulse which M. Coste and his 
followers have given to this science, it can hardly be considered as yet 
